Detecting genetic epistasis by differential departure from independence.

Countering prior beliefs that epistasis is rare, genomics advancements suggest the other way. Current practice often filters out genomic loci with low variant counts before detecting epistasis. We argue that this practice is far from optimal because it can throw away strong epistatic patterns. Instead, we present the compensated Sharma-Song test to infer genetic epistasis in genome-wide association studies by differential departure from independence. The test does not require a minimum number of replicates for each variant. We also introduce algorithms to simulate epistatic patterns that differentially depart from independence. Using two simulators, the test performed comparably to the original Sharma-Song test when variant frequencies at a locus are marginally uniform; encouragingly, it has a marked advantage over alternatives when variant frequencies are marginally nonuniform. The test further revealed uniquely clean epistatic variants associated with chicken abdominal fat content that are not prioritized by other methods. Genes involved in most numbers of inferred epistasis between single nucleotide polymorphisms (SNPs) belong to pathways known for obesity regulation; many top SNPs are located on chromosome 20 and in intergenic regions. Measuring differential departure from independence, the compensated Sharma-Song test offers a practical choice for studying epistasis robust to nonuniform genetic variant frequencies.

Fundamental gene network rewiring at the second order within and across mammalian systems.

MOTIVATION: Genetic or epigenetic events can rewire molecular networks to induce extraordinary phenotypical divergences. Among the many network rewiring approaches, no model-free statistical methods can differentiate gene-gene pattern changes not attributed to marginal changes. This may obscure fundamental rewiring from superficial changes. RESULTS: Here we introduce a model-free Sharma-Song test to determine if patterns differ in the second order, meaning that the deviation of the joint distribution from the product of marginal distributions is unequal across conditions. We prove an asymptotic chi-squared null distribution for the test statistic. Simulation studies demonstrate its advantage over alternative methods in detecting second-order differential patterns. Applying the test on three independent mammalian developmental transcriptome datasets, we report a lower frequency of co-expression network rewiring between human and mouse for the same tissue group than the frequency of rewiring between tissue groups within the same species. We also find second-order differential patterns between microRNA promoters and genes contrasting cerebellum and liver development in mice. These patterns are enriched in the spliceosome pathway regulating tissue specificity. Complementary to previous mammalian comparative studies mostly driven by first-order effects, our findings contribute an understanding of system-wide second-order gene network rewiring within and across mammalian systems. Second-order differential patterns constitute evidence for fundamentally rewired biological circuitry due to evolution, environment or disease. AVAILABILITY AND IMPLEMENTATION: The generic Sharma-Song test is available from the R package 'DiffXTables' at https://cran.r-project.org/package=DiffXTables. Other code and data are described in Section 2. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Validity and reliability of global ratings of satisfaction with epilepsy surgery.

OBJECTIVE: We aimed to assess the reliability and validity of single-item global ratings (GR) of satisfaction with epilepsy surgery. METHODS: We recruited 240 patients from four centers in Canada and Sweden who underwent epilepsy surgery ≥1 year earlier. Participants completed a validated questionnaire on satisfaction with epilepsy surgery (the ESSQ-19), plus a single-item GR of satisfaction with epilepsy surgery twice, 4-6 weeks apart. They also completed validated questionnaires on quality of life, depression, health state utilities, epilepsy severity and disability, medical treatment satisfaction and social desirability. Test-retest reliability of the GR was assessed with the intra-class correlation coefficient (ICC). Construct and criterion validity were examined with polyserial correlations between the GR measure of satisfaction and validated questionnaires and with the ESSQ-19 summary score. Non-parametric rank tests evaluated levels of satisfaction, and ROC analysis assessed the ability of GRs to distinguish among clinically different patient groups. RESULTS: Median age and time since surgery were 42 years (IQR 32-54) and 5 years (IQR 2-8), respectively. The GR demonstrated good to excellent test-retest reliability (ICC = 0.76; 95% CI 0.67-0.84) and criterion validity (0.85; 95% CI 0.81-0.89), and moderate correlations in the expected direction with instruments assessing quality of life (0.59; 95% CI 0.51-0.63), health utilities (0.55; 95% CI 0.45-0.65), disability (-0.51; 95% CI -0.41, -0.61), depression (-0.48; 95% CI -0.38, -0.58), and epilepsy severity (-0.48; 95% CI -0.38, -0.58). As expected, correlations were lower for social desirability (0.40; 95% CI 0.28-0.52) and medical treatment satisfaction (0.33; 95% CI 0.21-0.45). The GR distinguished participants who were seizure-free (AUC 0.75; 95% CI 0.67-0.82), depressed (AUC 0.75; 95% CI 0.67-0.83), and self-rated as having more severe epilepsy (AUC 0.78; 95% CI 0.71-0.85) and being more disabled (AUC 0.82; 95% CI 0.74-0.90). SIGNIFICANCE: The GR of epilepsy surgery satisfaction showed good measurement properties, distinguished among clinically different patient groups, and appears well-suited for use in clinical practice and research.

Predicting postoperative epilepsy surgery satisfaction in adults using the 19-item Epilepsy Surgery Satisfaction Questionnaire and machine learning.

OBJECTIVE: The 19-item Epilepsy Surgery Satisfaction Questionnaire (ESSQ-19) is a validated and reliable post hoc means of assessing patient satisfaction with epilepsy surgery. Prediction models building on these data can be used to counsel patients. METHODS: The ESSQ-19 was derived and validated on 229 patients recruited from Canada and Sweden. We isolated 201 (88%) patients with complete clinical data for this analysis. These patients were adults (≥18 years old) who underwent epilepsy surgery 1 year or more prior to answering the questionnaire. We extracted each patient's ESSQ-19 score (scale is 0-100; 100 represents complete satisfaction) and relevant clinical variables that were standardized prior to the analysis. We used machine learning (linear kernel support vector regression [SVR]) to predict satisfaction and assessed performance using the R2 calculated following threefold cross-validation. Model parameters were ranked to infer the importance of each clinical variable to overall satisfaction with epilepsy surgery. RESULTS: Median age was 41 years (interquartile range [IQR] = 32-53), and 116 (57%) were female. Median ESSQ-19 global score was 68 (IQR = 59-75), and median time from surgery was 5.4 years (IQR = 2.0-8.9). Linear kernel SVR performed well following threefold cross-validation, with an R2 of .44 (95% confidence interval = .36-.52). Increasing satisfaction was associated with postoperative self-perceived quality of life, seizure freedom, and reductions in antiseizure medications. Self-perceived epilepsy disability, age, and increasing frequency of seizures that impair awareness were associated with reduced satisfaction. SIGNIFICANCE: Machine learning applied postoperatively to the ESSQ-19 can be used to predict surgical satisfaction. This algorithm, once externally validated, can be used in clinical settings by fixing immutable clinical characteristics and adjusting hypothesized postoperative variables, to counsel patients at an individual level on how satisfied they will be with differing surgical outcomes.

Development and validation of the Epilepsy Surgery Satisfaction Questionnaire (ESSQ-19).

OBJECTIVE: No validated tools exist to assess satisfaction with epilepsy surgery. We aimed to develop and validate a new measure of patient satisfaction with epilepsy surgery, the 19-item Epilepsy Surgery Satisfaction Questionnaire (ESSQ-19). METHODS: An initial 31-item measure was developed based on literature review, patient focus groups, thematic analysis, and Delphi panels. The questionnaire was administered twice, 4-6 weeks apart, to 229 adults (≥18 years old) who underwent epilepsy surgery ≥1 year earlier, at three centers in Canada and one in Sweden. Participants also completed seven validated questionnaires to assess construct validity. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) assessed the factorial structure of the questionnaire. Cronbach alpha and intraclass correlation coefficients (ICCs) assessed the internal consistency and test-retest reliability of the ESSQ-19. Spearman and polyserial correlations assessed construct validity. RESULTS: Median age of participants and time since surgery were 42 years (interquartile range [IQR] = 32-54) and 5 years (IQR = 2-8.75), respectively. EFA and CFA yielded 18 items that segregated into four domains (mean score [SD]), namely, seizure control (76.4 [25]), psychosocial functioning (67.3 [26]), surgical complications (84 [22]), and recovery from surgery (73 [24]), one global satisfaction item, and a summary global score (74 [21]). The domain and summary scores demonstrated good to excellent internal reliability (Cronbach ⍺ range = .84-.95) and test-retest reliability (ICC range = 0.71-0.85). Construct validity was supported by predicted correlations with other instruments. SIGNIFICANCE: The ESSQ-19 is a new, valid, and reliable measure of patient satisfaction with epilepsy surgery that can be used in clinical and research settings.

A novel signal sequence negative multimeric glycosomal protein required for cell cycle progression of Leishmania donovani parasites.

Expression of the intracellular form amastigote specific genes in the Leishmania donovani parasite plays a major role in parasite replication in the macrophage. In the current work, we have characterized a novel hypothetical gene, Ld30b that is specifically transcribed in the intracellular stage of the parasite. The recombinant Ld30b protein exists as a pentamer in solution as identified by native-PAGE and size exclusion gel chromatography. Structural analysis using circular dichroism and molecular modeling indicate that Ld30b belongs to family of cAMP-dependent protein kinase type I-alpha regulatory subunit. Co-localization immunofluorescence microscopy and western blot analyses (using anti-Ld30b antibody and anti-hypoxanthine-guanine phosphoribosyl transferase, a glycosome marker) on the isolated parasite glycosome organelle fractions show that Ld30b is localized in glycosome, though lacked a glycosome targeting PTS1/2 signal in the protein sequence. Episomal expression of Ld30b in the parasite caused the arrest of promastigotes and amastigotes growth in vitro. Cell cycle analysis using flow cytometry indicates that these parasites are arrested in 'sub G0/G1' phase of the cell cycle. Single allele knockout of Ld30b in the parasite similarly attenuated its growth by accumulation of cells in the S phase of cell cycle, thus confirming the probable importance of appropriate level of protein in the cells. Studying such intracellular stage expressing genes might unravel novel regulatory pathways for the development of drugs or vaccine candidates against leishmaniasis.

Crucial residues in falcipains that mediate hemoglobin hydrolysis.

Falcipain-2 (FP2) and falcipain-3 (FP3) constitute the major hemoglobinases of Plasmodium falciparum. Previous biochemical and structural studies have explained the mechanism of inhibition of these enzymes by small molecules. However, a residue-level protein-protein interaction (PPI) with its natural macromolecular substrate, hemoglobin is not fully characterized. Earlier studies have identified a short motif in the C-terminal of FP2, an exosite protruding away from the active site, essential for hemoglobin degradation. Our structural and mutagenesis studies suggest that hemoglobin interacts with FP2 via specific interactions mediated by Glu185 and Val187 within the C-terminal motif, which are essential for hemoglobin binding. Since FP3 is also a major hemoglobinase and essential for parasite survival, we further demonstrate its interactions with hemoglobin. Our results suggest that Asp194 of FP3 is required for hemoglobin hydrolysis and residue-swap experiments confirmed that this position is functionally conserved between the two hemoglobinases. Residues involved in protein-protein interactions constitute important targets for drug-mediated inhibition. Targeting protein-protein interactions at exosites may likely be less susceptible to emergence of drug resistance and thus is a new field to explore in malaria.

Understanding the complex formation of falstatin; an endogenous macromolecular inhibitor of falcipains.

Proteolytic activity constitutes a fundamental process essential for the survival of the malaria parasite and is thus highly regulated. Falstatin, a protease inhibitor of Plasmodium falciparum, tightly regulates the activity of cysteine hemoglobinases, falcipain-2 and 3 (FP2, FP3), by inhibiting FP2 through a single surface exposed loop. However, the multimeric nature of falstatin and its interaction with FP2 remained unexplored. Here we report that the N-terminal falstatin region is highly disordered, and needs chaperone activity (heat-shock protein 70, HSP70) for its folding. Protein-protein interaction assays showed a significant interaction between falstatin and HSP70. Further, characterization of the falstatin multimer through a series of biophysical techniques identified the formation of a falstatin decamer, which was extremely thermostable. Computational analysis of the falstatin decamer showed the presence of five falstatin dimers, with each dimer aligned in a head-to-tail orientation. Further, the falstatin C-terminal region was revealed to be primarily involved in the oligomerization process. Stoichiometric analysis of the FP2-falstatin multimer showed the formation of a heterooligomeric complex in a 1:1 ratio, with the participation of ten subunits of each protein. Taken together, our results report a novel protease-inhibitor complex and strengthens our understanding of the regulatory mechanisms of major plasmodium hemoglobinases.

Knowledge, Practice and Barriers on Cervical Cancer Screening among Married Women.

BACKGROUND: Cervical cancer is a most common preventable public health problem. Despite availability of various screening services at Biratnagar, many barriers restrict its utilization. So, we aimed to assess the knowledge, practice and barriers of cervical cancer screening among 30-60 years married women in Biratnagar, Morang, Nepal. METHODS: We conducted a community based cross sectional study in Biratnagar Morang from December 2020 to December 2021. Consecutive sampling technique was used to collect data from 280 married women of 30-60 years. Ethical approval was obtained from Nepal Health Research Council and informed consent was taken from study participants. Data was collected by face to face interview using a semi structured questionnaire. RESULTS: All participants had heard of cervical cancer. Most (93.9%) responded to multiple sexual partners as a risk factor and 97.9% responded to excessive vaginal bleeding as a symptom. Most (97.1%) responded that cervical cancer is preventable and 44.1% were aware of pap smear test. Eighty-four (30%) participants had ever been screened for cervical cancer. Unavailability of health insurance (85.2%), high cost of treatment (83.1%), lack of nearby service availability (70.9%), embarrassment (44.8%), presence of male doctors (43.8%), problems in time management (28.01%), no advice from health care providers (22.9%), unaware of screening (15.8%) and beliefs on traditional healers (7.1%) were barriers. CONCLUSIONS: In comparison to knowledge, practice of cervical cancer screening is low suggesting existence of know-do gap. Various barriers that prevent cervical cancer screening were evident.

Medicinal Herbs from Phytoinformatics: An Aid for Skin Burn Management.

Skin burn injury is the most common cause of trauma that is still considered a dreadful condition in healthcare emergencies around the globe. Due to the availability of a variety of regimes, their management remains a dynamical challenge for the entire medical and paramedical community. Indeed, skin burn injuries are accompanied by a series of several devastating events that lead to sepsis and multiple organ dysfunction syndromes. Hence, the challenge lies in the development of a better understanding as well as clear diagnostic criteria and predictive biomarkers, which are important in their management. Though there are several regimes available in the market, there are still numerous limitations and challenges in the management. In this review article, we have discussed the various biomarkers that could be targeted for managing skin burn injuries. Instead of focusing on allopathic medication that has its adverse events per se, we have discussed the history, ethnopharmacology properties, and prospects of identified phytomedicines from a well-established herbal informatics model. This review article not only discusses the benefits of scrutinized phytocompounds but also the development of novel druggable phyto-compounds to target skin burn injury at a lower cost with no adverse effects.

Crystal structure of ArOYE6 reveals a novel C-terminal helical extension and mechanistic insights into the distinct class III OYEs from pathogenic fungi.

Old yellow enzymes (OYEs) play a critical role in antioxidation, detoxification and ergot alkaloid biosynthesis processes in various organisms. The yeast- and bacteria-like OYEs have been structurally characterized earlier, however, filamentous fungal pathogens possess a novel OYE class, that is, class III, whose biochemical and structural intricacies remain unexplored to date. Here, we present the 1.6 Å X-ray structure of a class III member, OYE 6 from necrotrophic fungus Ascochyta rabiei (ArOYE6), in flavin mononucleotide (FMN)-bound form (PDB ID-7FEV) and provide mechanistic insights into their catalytic capability. We demonstrate that ArOYE6 exists as a monomer in solution, forms (ß/α)8 barrel structure harbouring non-covalently bound FMN at cofactor binding site, and utilizes reduced nicotinamide adenine dinucleotide phosphate as its preferred reductant. The large hydrophobic cavity situated above FMN, specifically accommodates 12-oxo-phytodienoic acid and N-ethylmaleimide substrates as observed in ArOYE6-FMN-substrate ternary complex models. Site-directed mutations in the conserved catalytic (His196, His199 and Tyr201) and FMN-binding (Lys249 and Arg348) residues render the enzyme inactive. Intriguingly, the ArOYE6 structure contains a novel C-terminus (369-445 residues) made of three α-helices, which stabilizes the FMN binding pocket as its mutation/truncation lead to complete loss of FMN binding. Moreover, the loss of the extended C-terminus does not alter the monomeric nature of ArOYE6. In this study, for the first time, we provide the structural and biochemical insights for a fungi-specific class III OYE homologue and dissect the oxidoreductase mechanism. Our findings hold broad biological significance during host-fungus interactions owing to the conservation of this class among pathogenic fungi, and would have potential implications in the pharmacochemical industry.

WITHDRAWN: A phosphate transporter from the root endophytic fungus Piriformospora indica plays a role in phosphate transport to the host plant.

Because pure cultures and a stable transformation system are not available for arbuscular mycorrhizal fungi, the role of their phosphate transporters for the symbiotic interaction with the plant up till now could not be studied. Here we report the cloning and the functional analysis of a gene encoding a phosphate transporter (PiPT) from the root endophytic fungus Piriformospora indica, which can be grown axenically. The PiPT polypeptide belongs to the major facilitator superfamily. Homology modeling reveals that PiPT exhibits twelve transmembrane helices divided into two halves connected by a large hydrophilic loop in the middle. The function of the protein encoded by PiPT was confirmed by complementation of a yeast phosphate transporter mutant. The kinetic analysis of PiPT (K(m) 25 mum) reveals that it belongs to the high affinity phosphate transporter family (Pht1). Expression of PiPT was localized to the external hyphae of P. indica colonized with maize plant root, which suggests that external hyphae are the initial site of phosphate uptake from the soil. To understand the physiological role of PiPT, knockdown transformants of the gene were prepared using electroporation and RNA interference. Knockdown transformants transported a significantly lower amount of phosphate to the host plant than wild-type P. indica. Higher amounts of phosphate were found in plants colonized with wild-type P. indica than that of non-colonized and plants colonized with knockdown PiPT P. indica. These observations suggest that PiPT is actively involved in the phosphate transportation and, in turn, P. indica helps improve the nutritional status of the host plant.

Non-alcoholic fatty liver disease in patients with hypothyroidism presenting at a rural tertiary care centre in north India.

Apart from its association with metabolic syndrome and diabetes mellitus, non-alcoholic fatty liver disease (NAFLD) has been thought to be linked with other endocrine and metabolic disorders. Recent data suggest that hypothyroidism may be a significant risk factor for development and progression of NAFLD. The present study was conducted to evaluate the presence of NAFLD in patients with hypothyroidism presenting to a rural tertiary care centre in north India. The diagnosis of NAFLD was made on the basis of radiological findings and derangement of liver enzymes. Our findings showed that ultrasonographic evidence of fatty liver as well as increase in the serum transaminase level above normal range were significantly higher in hypothyroidism patients as compared with controls. On multivariate regression analysis of the patients' data, the presence of hypothyroidism was independently associated with risk of NAFLD. We therefore conclude that hypothyroidism is a significant independent risk factor.

QTc prolongation in patients of cirrhosis and its relation with disease severity: An observational study from a rural teaching hospital.

INTRODUCTION: Cirrhotic cardiomyopathy is characterised by increased baseline cardiac output, systolic and diastolic dysfunction, diminished cardiovascular response to stressful stimuli and electrophysiological abnormalities in patients of cirrhosis in the absence of any underlying cardiac disease. QTc prolongation has been described as a common electrocardiographic abnormality in cirrhosis patients. AIMS AND OBJECTIVES: This study was done to evaluate the prevalence of QTc changes in patients of cirrhosis coming to a rural tertiary care centre and to analyse its correlation with disease severity. MATERIALS AND METHODS: The present study was conducted on 100 patients suffering from cirrhosis of liver presented to the department of medicine. Around 100 age and sex-matched individuals were recruited as controls. The Child-Pugh score was used to determine the disease severity in cirrhosis patients. Standard 12-lead ECG was recorded in all cases and controls. RESULTS: Prolongation of QTc interval on ECG was observed in the majority (80%) of cirrhosis patients and it was significantly higher as compared to the healthy controls (P <0.01). The prolongation of QTc was significantly associated with the duration of disease (P <0.05) and disease severity as measured by the Child-Pugh score (P <0.01). CONCLUSION: QTc prolongation on ECG may be an early marker of cardiac involvement in patients of cirrhosis and is significantly associated with disease severity.

Bowen's disease of the nipple in a young man with AIDS: a case report.

Bowen's disease, or squamous cell carcinoma in situ (SCCIS) of the skin, is a malignant neoplasm restricted to the epidermis, without evidence of dermal invasion. It usually develops in sun-exposed area of skin, but other sites can also be affected. Bowen's disease of the nipple is extremely rare and has thus far been reported only in women. We present the case of Bowen's disease of the nipple in an HIV-positive male patient who presented with a scaly lesion on nipple for one year. He also had past genital infection with human papillomavirus, but he was found to be negative for high-risk subtypes. Biopsy of the lesion revealed SCCIS of the nipple areola complex, with extension into the underlying lactiferous ducts of the breast. There was no evidence of invasive carcinoma. The patient was treated with a simple mastectomy with sentinel lymph node biopsy. With the advent of highly active antiretroviral treatment, chronic non-HIV related conditions have become more important, male breast cancer being one of them. To the best of our knowledge, this is the first reported case in the worldwide literature of Bowen's disease of the nipple in a young immunocompromised male patient. More aggressive therapy in HIV-positive male patients presenting with precancerous and cancerous breast lesions is recommended.

Positive association between increased popliteal artery vessel wall thickness and generalized osteoarthritis: is OA also part of the metabolic syndrome?

PURPOSE: The purpose of the study was to determine if a positive association exists between arterial vessel wall thickness and generalized osteoarthritis (OA). Our hypothesis is that generalized OA is another facet of the metabolic syndrome. MATERIALS AND METHODS: The medical ethical review board of our institution approved the study. Written informed consent was obtained from each patient prior to the study. Magnetic resonance (MR) images of the knee were obtained in 42 patients who had been diagnosed with generalized OA at multiple joint sites. Another 27 MR images of the knee were obtained from a matched normal (non-OA) reference population. Vessel wall thickness of the popliteal artery was quantitatively measured by dedicated software. Linear regression models were used to investigate the association between vessel wall thickness and generalized OA. Adjustments were made for age, sex, and body mass index (BMI). Confidence intervals (CI) were computed at the 95% level and a significance level of alpha = 0.05 was used. RESULTS: Patients in the generalized OA population had a significant higher average vessel wall thickness than persons from the normal reference population (p < or = alpha), even when correction was made for sex, age, and BMI. The average vessel wall thickness of the popliteal artery was 1.09 mm in patients with generalized OA, and 0.96 mm in the matched normal reference population. CONCLUSION: The association found between increased popliteal artery vessel wall thickness and generalized osteoarthritis suggests that generalized OA might be another facet of the metabolic syndrome.

Primary squamous cell carcinoma of breast in background of phyllodes tumor--a case report.

Primary squamous cell carcinoma of the breast (PSCCB) is a rare and generally aggressive malignancy constituting < 0.1% of invasive breast cancers. This report describes a case of primary squamous cell carcinoma of the breast that emerged in association with a phyllodes tumor. Our patient, a 59-year-old female, presented with a rapidly growing 9x12 cm breast mass. She underwent modified radical mastectomy followed by chemotherapy with carboplatin and docetaxel. She is free of disease one year after diagnosis. Clinicians should be aware of the aggressive behavior of this tumor, and adequate investigation should be done to rule out metastasis from another primary site.

Comparative structure analysis of the ETSi domain of ERG3 and its complex with the E74 promoter DNA sequence. Corrigendum.

The article by Sharma et al. [(2018), Acta Cryst. F74, 656-663] is corrected.

Metacaspase-3 of Plasmodium falciparum: An atypical trypsin-like serine protease.

Metacaspases are clan CD cysteine peptidases found in plants, fungi and protozoa that possess a conserved Peptidase_C14 domain, homologous to the human caspases and a catalytic His/Cys dyad. Earlier reports have indicated the role of metacaspases in cell death; however, metacaspases of human malaria parasite remains poorly understood. In this study, we aimed to functionally characterize a novel malarial protease, P. falciparum metacaspase-3 (PfMCA3). Unlike other clan CD peptidases, PfMCA3 has an atypical active site serine (Ser1865) residue in place of canonical cysteine and it phylogenetically forms a distinct branch across the species. To investigate whether this domain retains catalytic activity, we expressed, purified and refolded the Peptidase_C14 domain of PfMCA3 which was found to express in all asexual stages. PfMCA3 exhibited trypsin-like serine protease activity with ser1865 acting as catalytic residue to cleave trypsin oligopeptide substrate. PfMCA3 is inhibited by trypsin-like serine protease inhibitors. Our study found that PfMCA3 enzymatic activity was abrogated when catalytic serine1865 (S1865A) was mutated. Moreover, PfMCA3 was found to be inactive against caspase substrate. Overall, our study characterizes a novel metacaspase of P. falciparum, different from human caspases and not responsible for the caspase-like activity, therefore, could be considered as a potential chemotherapeutic target.