Naturally acquired immunity to Plasmodium pitheci in Bornean orangutans (Pongo pygmaeus).

Naturally acquired immunity to the different types of malaria in humans occurs in areas of endemic transmission and results in asymptomatic infection of peripheral blood. The current study examined the possibility of naturally acquired immunity in Bornean orangutans, Pongo pygmaeus, exposed to endemic Plasmodium pitheci malaria. A total of 2140 peripheral blood samples were collected between January 2017 and December 2022 from a cohort of 135 orangutans housed at a natural forested Rescue and Rehabilitation Centre in West Kalimantan, Indonesia. Each individual was observed for an average of 4.3 years during the study period. Blood samples were examined by microscopy and polymerase chain reaction for the presence of plasmodial parasites. Infection rates and parasitaemia levels were measured among age groups and all 20 documented clinical malaria cases were reviewed to estimate the incidence of illness and risk ratios among age groups. A case group of all 17 individuals that had experienced clinical malaria and a control group of 34 individuals having an event of >2000 parasites µL−1 blood but with no outward or clinical sign of illness were studied. Immature orangutans had higher-grade and more frequent parasitaemia events, but mature individuals were more likely to suffer from clinical malaria than juveniles. The case orangutans having patent clinical malaria were 256 times more likely to have had no parasitaemia event in the prior year relative to asymptomatic control orangutans. The findings are consistent with rapidly acquired immunity to P. pitheci illness among orangutans that wanes without re-exposure to the pathogen.

Dephospho-Coenzyme A Kinase Is an Exploitable Drug Target against Plasmodium falciparum: Identification of Selective Inhibitors by High-Throughput Screening of a Large Chemical Compound Library.

Malaria is a mosquito-borne fatal infectious disease that affects humans and is caused by Plasmodium parasites, primarily Plasmodium falciparum. Widespread drug resistance compels us to discover novel compounds and alternative drug discovery targets. The coenzyme A (CoA) biosynthesis pathway is essential for the malaria parasite P. falciparum. The last enzyme in CoA biosynthesis, dephospho-CoA kinase (DPCK), is essential to the major life cycle development stages but has not yet been exploited as a drug target in antimalarial drug discovery. We performed a high-throughput screen of a 210,000-compound library using recombinant P. falciparum DPCK (PfDPCK). A high-throughput enzymatic assay using a 1,536-well platform was developed to identify potential PfDPCK inhibitors. PfDPCK inhibitors also inhibited parasite growth in a P. falciparum whole-cell asexual blood-stage assay in both drug-sensitive and drug-resistant strains. Hit compounds were selected based on their potency in cell-free (PfDPCK) and whole-cell (Pf3D7 and PfDd2) assays, selectivity over the human orthologue (HsCOASY) and no cytotoxicity (HepG2). The compounds were ranked using a multiparameter optimization (MPO) scoring model, and the specific binding and the mechanism of inhibition were investigated for the most promising compounds.

Cellulosimicrobium marinum sp. nov., an actinobacterium isolated from sea sediment.

A novel Gram stain positive actinobacterium, designated RS-7-4(T), was isolated from a sea sediment sample collected in Indonesia, and its taxonomic position was investigated using a polyphasic approach. Strain RS-7-4(T) was observed to form vegetative hyphae in the early phase of growth, but the hyphae eventually fragmented into short rods to coccoid cells. Growth occurred at 15-37 °C, pH 6.0-11.0 and in the presence of 0-7 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain RS-7-4(T) was closely related to the members of the genus Cellulosimicrobium, with a similarity range of 98.08-99.10 %. The peptidoglycan type of strain RS-7-4(T) was found to be A4α L-Lys-L-Thr-D-Asp. The predominant menaquinone was MK-9(H4), and the major fatty acids were anteiso-C15:0, iso-C15:0 and anteiso-C17:0. The DNA G+C content was 75.6 mol%. These chemotaxonomic features corresponded to those of the genus Cellulosimicrobium. Meanwhile, the results of DNA-DNA hybridization, and physiological and biochemical tests revealed that strain RS-7-4(T) was different from the recognized species of the genus Cellulosimicrobium. Therefore, strain RS-7-4(T) represents a novel species of the genus Cellulosimicrobium, for which the name Cellulosimicrobium marinum sp. nov. is proposed. The type strain is RS-7-4(T) (=NBRC 110994(T) =InaCC A726(T)).

Kocuria pelophila sp. nov., an actinobacterium isolated from the rhizosphere of a mangrove.

A novel spherical actinobacterium, designated RS-2-3T, was isolated from the rhizosphere of a mangrove growing on Rambut Island, Indonesia, and its taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that strain RS-2-3T was related to the members of the genus Kocuria. The highest 16S rRNA gene sequence similarity value was observed with Kocuria marina KMM 3905T (97.0 %). The peptidoglycan type of strain RS-2-3T was found to be A3α with an interpeptide bridge comprising l-Ala4-5. The predominant menaquinone was MK-7(H2) and the major fatty acids were anteiso-C15 : 0 and iso-C15 : 0. The DNA G+C content was 71.8 mol%. These characteristics were consistent with those of members of the genus Kocuria. Meanwhile, physiological and biochemical characteristics revealed that strain RS-2-3T differed from the species of the genus Kocuria with validly published names. Therefore, strain RS-2-3T represents a novel species of the genus Kocuria, for which the name Kocuria pelophila sp. nov. is proposed. The type strain is RS-2-3T (=NBRC 110990T=InaCC A704T).

Actinoplanes tropicalis sp. nov. and Actinoplanes cibodasensis sp. nov., isolated from leaf litter.

Two actinomycete strains, designated LIPI11-2-Ac034T and LIPI11-2-Ac042T, were isolated from leaf litter collected from Cibodas Botanical Garden, West Java, Indonesia. Phylogenetic analysis based on 16S rRNA gene sequences suggested that both isolates belong to the genus Actinoplanes. These isolates were closely related to Actinoplanes ferrugineus and Actinoplanes durhamensis with similarity values of 98.2 % and 97.7 % respectively, for strain LIPI11-2-Ac034T, and 99.0 % and 97.4-97.7 % respectively for strain LIPI11-2-Ac042T. Both isolates grew well on ISP 7 medium with brown soluble pigment production. Spores were motile and sporangia were irregular. The isolates contained meso-diaminopimelic acid in cell-wall hydrolysates, and mannose, glucose and galactose in whole-cell hydrolysates. The predominant menaquinone of strain LIPI11-2-Ac034T was MK-9(H4) while that of strain LIPI11-2-Ac042T was MK-9(H6). The major cellular fatty acids were iso-C16 : 0, iso-C15 : 0 and anteiso-C15 : 0 for strain LIPI11-2-Ac034T, and iso-C16 : 0, anteiso-C15 : 0, iso-C15 : 0 and anteiso-C17 : 0 for strain LIPI11-2-Ac042T. Phosphatidylethanolamine was detected as the diagnostic polar lipid. The DNA G+C contents of strains LIPI11-2-Ac034T and LIPI11-2-Ac042T were 71.5 and 70.7 mol%, respectively. Based on the differential phenotypic characteristics and the results of DNA-DNA hybridization and phylogenetic analysis, it is proposed that strains LIPI11-2-Ac034T and LIPI11-2-Ac042T represent two novel species of the genus Actinoplanes, for which the names Actinoplanes tropicalis sp. nov. (type strain LIPI11-2-Ac034T = InaCC A459T = NBRC 110973T) and Actinoplanes cibodasensis sp. nov. (type strain LIPI11-2-Ac042T = InaCC A458T = NBRC 110974T) are proposed.

Cryptosporangium cibodasense sp. nov., isolated from leaf litter in Indonesia.

A novel actinomycete strain, designated LIPI11-2-Ac046T, was isolated from a leaf litter sample obtained from Cibodas Botanical Garden, West Java, Indonesia, using the rehydration and centrifugation method. The taxonomic status of this organism was established using a polyphasic approach. Comparative 16S rRNA gene sequence analysis revealed that strain LIPI11-2-Ac046T had the closest sequence similarities with members of the genus Cryptosporangium (97.99-98.90 %). The strain grew well on ISP 4 and ISP 5 media and formed sporangia. Spores of this strain were motile. The strain grew in the presence of 0-2 % (w/v) NaCl and the temperature range of 15-28 8C. The cell-wall hydrolysate contained meso-diaminopimelic acid as the diagnostic diamino acid and the whole-cell hydrolysate contained mannose, glucose, galactose, ribose and xylose, together with one unidentified O-methyl-pentose. The predominant menaquinones were MK-9(H4), MK-9(H6) and MK-9(H8), and the major polar lipid was phosphatidylethanolamine. The major cellular fatty acids were C18 : 1ω9c, iso-C16 : 0, C16 : 0 andC17 : 1ω9c. These phenotypic characteristics corresponded to those of the genus Cryptosporangium. Meanwhile, the results of DNA-DNA hybridization as well as physiological and biochemical analyses distinguished strain LIPI11-2-Ac046T from known members of the genus Cryptosporangium. On the basis of these data, it is proposed that strain LIPI11-2-Ac046T represents a novel species of the genus Cryptosporangium, with the name Cryptosporangium cibodasense sp. nov. The type strain is LIPI11-2-Ac046T (=InaCC A457T=NBRC 110976T).

Serinibacter tropicus sp. nov., an actinobacterium isolated from the rhizosphere of a mangrove, and emended description of the genus Serinibacter.

A novel Gram-stain-positive actinobacterium, designated PS-14-7(T), was isolated from the rhizosphere of a mangrove on Pramuka Island, Indonesia, and its taxonomic position was investigated using a polyphasic approach. The peptidoglycan type of strain PS-14-7(T) was A4α and lysine was the diagnostic diamino acid of the peptidoglycan. The predominant menaquinone was MK-8(H4) and the major fatty acids were anteiso-C(15 : 0), C(16 : 0) and iso-C(16 : 0). The DNA G+C content was 72.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain PS-14-7(T) was closely related to Serinibacter salmoneus Kis4-28(T) (99.6%). However, DNA-DNA hybridization and phenotypic characteristics revealed that strain PS-14-7(T) differed from Serinibacter salmoneus . Therefore, strain PS-14-7(T) represents a novel species of the genus Serinibacter , for which the name Serinibacter tropicus sp. nov. is proposed. The type strain is PS-14-7(T) ( = NBRC 110108(T) = InaCC A 515(T)). An emended description of the genus Serinibacter is also proposed.

Tropicihabitans flavus gen. nov., sp. nov., a new member of the family Cellulomonadaceae.

Two novel Gram-stain positive actinobacteria, designated PS-14-16(T) and RS-7-1, were isolated from the rhizosphere of a mangrove and sea sediment, respectively, and their taxonomic positions were investigated by a polyphasic approach. Both strains were observed to form vegetative hyphae in the early phase of growth but the hyphae eventually fragment into short rods to coccoid cells. The peptidoglycan type of both strains was found to be A4α. Their predominant menaquinone was identified as MK-9(H4) and the major fatty acid as anteiso-C(15:0). The DNA G+C content was determined to be 68.4-68.5 mol%. 16S rRNA gene sequencing revealed that strains PS-14-16(T) and RS-7-1 were related to members of the family Cellulomonadaceae. Their nearest phylogenetic neighbour was found to be Sediminihabitans luteus, which is currently the only species of the genus Sediminihabitans, with a similarity of 97.94%. However, strains PS-14-16(T) and RS-7-1 were distinguishable from the members of the genus Sediminihabitans and the other genera within the family Cellulomonadaceae in terms of chemotaxonomic characteristics and phylogenetic relationship. The results of DNA-DNA hybridization experiments indicated that strains PS-14-16(T) and RS-7-1 belong to the same species. Strains PS-14-16(T) and RS-7-1 are concluded to represent a novel genus and species of the family Cellulomonadaceae, for which the name Tropicihabitans flavus gen. nov., sp. nov. is proposed. The type strain of T. flavus is PS-14-16(T) (=NBRC 110109(T) = IanCC A 516(T)). [corrected].

Profile and in silico analysis of metabolite compounds of the endophytic fungus Alternaria alternata K-10 from Drymoglossum piloselloides as antioxidants and antibacterials.

Endophytic fungi are known for producing secondary metabolites with valuable biological activities, including antiviral, anticancer, antibacterial, and antioxidant properties. This study aims to evaluate an endophytic fungus from Dragon Scales leaves (Drymoglossum piloselloides) and analyze its metabolites as antioxidants and antibacterials. In this study, an endophytic fungus was isolated from the leaves of Dragon Scales (D. piloselloides) and identified using molecular analysis of the Internal Transcribed Spacer (ITS) ribosomal RNA locus. The fungus was authenticated as Alternaria alternata strain K-10. Crude extracts were obtained using n-hexane and ethyl acetate and analyzed via GC-MS Shimadzu-QP 2010 Ultra with NIST spectral library. Antibacterial activity was observed against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa using the paper disc method, showing inhibition zones of 8.7-9.3 mm and 8.8-9.4 mm for ethyl acetate and n-hexane extracts, respectively. Ethyl acetate and n-hexane extracts exhibited strong antioxidant potential against 2,2-diphenyl-1-picrylhydrazil (DPPH) radical (IC50 values of 50.99 µg mL-1 and 74.44 µg mL-1, respectively). GC-MS analysis revealed 40 compounds in both extracts, some of which, including 2-ethylhexyl ester benzoic acid, benzo-b-dihydropyran-6-hydroxy-4-4-5-7-8-pentamethyl, diethyl phthalate, and octadecanoic acid, were identified through in silico analysis and found to possess antioxidant properties. These findings hold implications for potential applications of the plant and its biological constituent to be developed as lead compounds in the medical sector.

The effect of surfactant type on characteristics, skin penetration and anti-aging effectiveness of transfersomes containing amniotic mesenchymal stem cells metabolite products in UV-aging induced mice.

Transfersome has been developed to enhance dermal delivery of amniotic mesenchymal stem cell metabolite products (AMSC-MP). AMSC-MP contains many growth factors for managing skin aging, thus improving the quality of an adjusted life year. This study aims to determine the effect of surfactant types acting as the edge activator on transfersome-loading AMSC-MP. Transfersome was prepared by thin-layer hydration method and composed of l-α-phosphatidylcholine as a phospholipid and three types of surfactants, namely; cationic (stearylamine), anionic (sodium cholate), and nonionic surfactant (Tween 80) at a weight ratio of 85:15, respectively. Transfersomes were evaluated for physical characteristics, penetration, effectiveness, and safety. The results showed that sodium cholate, an anionic surfactant, produced the smallest transfersome particle size, i.e., 144.2 ± 3.2 nm, among all formulas. Trans-SA containing stearylamine had a positive charge of 41.53 ± 6.03 mV compared to Trans-SC and Trans-TW, whose respective charges were -56.9 ± 0.55 mV and -41.73 ± 0.86 mV. The small particle size and low negative value of zeta potential enabled high dermal penetration by transfersomes containing AMSC-MP, while the positive charge of stearylamine hindered its penetration of deeper skin layers. Trans-SC and Trans-TW produced higher collagen density values at 77.11 ± of 4.15% and 70.05 ± of 6.95%, than that of Trans-SA. All the AMSC-MP transfersomes were relatively safe with 0.5-1.0 macrophage cell numbers invaded the dermis per field of view. In conclusion, sodium cholate, an anionic surfactant, demonstrated considerable capacity as the edge activator of transfersome-loading AMSC-MP for skin anti-aging therapy.

Actinophytocola timorensis sp. nov. and Actinophytocola corallina sp. nov., isolated from soil.

Two actinomycete strains, ID05-A0653(T) and ID06-A0464(T), were isolated from soils of West Timor and Lombok island, respectively, in Indonesia. 16S rRNA gene sequence analysis clearly demonstrated that the isolates belonged to the family Pseudonocardiaceae and were closely related to the genus Actinophytocola. Strains ID05-A0653(T) and ID06-A0464(T) exhibited 98.1 and 98.2 % 16S rRNA gene sequence similarity, respectively, with Actinophytocola oryzae GMKU 367(T). The isolates grew well on ISP media and produced white aerial mycelium. Short spore chains were formed directly on the substrate mycelium. The isolates contained meso-diaminopimelic acid, arabinose and galactose as cell-wall components, MK-9(H(4)) as the sole isoprenoid quinone, iso-C(16 : 0) as the major cellular fatty acid and phosphatidylethanolamine as the diagnostic polar lipid. The DNA G+C contents of strains ID05-A0653(T) and ID06-A0464(T) were 69.7 and 71.2 mol%, respectively. On the basis of phenotypic characteristics, DNA-DNA relatedness and 16S rRNA gene sequence comparisons, strains ID05-A0653(T) and ID06-A0464(T) each represent a novel species of the genus Actinophytocola, for which the names Actinophytocola timorensis sp. nov. (type strain ID05-A0653(T)  = BTCC B-673(T)  = NBRC 105524(T)) and Actinophytocola corallina sp. nov. (type strain ID06-A0464(T)  = BTCC B-674(T)  = NBRC 105525(T)) are proposed.

Characterization of Plasmodium falciparum Pantothenate Kinase and Identification of Its Inhibitors From Natural Products.

Coenzyme A (CoA) is a well-known cofactor that plays an essential role in many metabolic reactions in all organisms. In Plasmodium falciparum, the most deadly among Plasmodium species that cause malaria, CoA and its biosynthetic pathway have been proven to be indispensable. The first and rate-limiting reaction in the CoA biosynthetic pathway is catalyzed by two putative pantothenate kinases (PfPanK1 and 2) in this parasite. Here we produced, purified, and biochemically characterized recombinant PfPanK1 for the first time. PfPanK1 showed activity using pantetheine besides pantothenate, as the primary substrate, indicating that CoA biosynthesis in the blood stage of P. falciparum can bypass pantothenate. We further developed a robust and reliable screening system to identify inhibitors using recombinant PfPanK1 and identified four PfPanK inhibitors from natural compounds.

Gentisyl alcohol and homogentisic acid: Plasmodium falciparum dihydroorotate dehydrogenase inhibitors isolated from fungi.

Two Indonesian fungi Aspergillus assiutensis BioMCC-f.T.7495 and Penicillium pedernalense BioMCC-f.T.5350 along with a Japanese fungus Hypomyces pseudocorticiicola FKI-9008 have been found to produce gentisyl alcohol (1), which inhibits Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) with an IC50 value of 3.4 µM. Another Indonesian fungus, Penicillium citrinum BioMCC-f.T.6730, produced an analog of 1, homogentisic acid (4), which also inhibits PfDHODH with an IC50 value of 47.6 µM.

Exploring natural microbial resources for the discovery of anti-malarial compounds.

Microorganisms in nature are highly diverse biological resources, which can be explored for drug discovery. Some countries including Brazil, Columbia, Indonesia, China, and Mexico, which are blessed with geographical uniqueness with diverse climates and display remarkable megabiodiversity, potentially provide microorganismal resources for such exploitation. In this review, as an example of drug discovery campaigns against tropical parasitic diseases utilizing microorganisms from such a megabiodiversity country, we summarize our past and on-going activities toward discovery of new antimalarials. The program was held in a bilateral collaboration between multiple Indonesian and Japanese research groups. In order to develop a new platform of drug discovery utilizing Indonesian bioresources under an international collaborative scheme, we aimed at: 1) establishment of an Indonesian microbial depository, 2) development of robust enzyme-based and cell-based screening systems, and 3) technology transfer necessary for screening, purification, and identification of antimalarial compounds from microbial culture broths. We collected, characterized, and deposited Indonesian microbes. We morphologically and genetically characterized fungi and actinomycetes strains isolated from 5 different locations representing 3 Indonesian geographical areas, and validated genetic diversity of microbes. Enzyme-based screening was developed against two validated mitochondrial enzymes from Plasmodium falciparum, dihydroorotate dehydrogenase and malate:quinone oxidoreductase, while cell-based proliferation assay was developed using the erythrocytic stage parasite of 3D7 strain. More than 17 thousands microbial culture extracts were subjected to the enzyme- and cell-based screening. Representative anti-malarial compounds discovered in this campaign are discussed, including a few isolated compounds that have been identified for the first time as anti-malarial compounds. Our antimalarial discovery campaign validated the Indonesian microbial library as a powerful resource for drug discovery. We also discuss critical needs for selection criteria for hits at each stage of screening and hit deconvolution such as preliminary extraction test for the initial profiling of the active compounds and dereplication techniques to minimize repetitive discovery of known compounds.

Microbial inhibitors active against Plasmodium falciparum dihydroorotate dehydrogenase derived from an Indonesian soil fungus, Talaromyces pinophilus BioMCC-f.T.3979.

An Indonesian soil fungus, Talaromyces pinophilus BioMCC-f.T.3979 was cultured to find novel scaffolds of Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) inhibitors. We obtained altenusin (1), which inhibits PfDHODH, with an IC50 value of 5.9 µM, along with other metabolites: mitorubrinol (2) and mitorubrinic acid (3). Compounds 1 and 2 inhibited PfDHODH but displayed no activity against the human orthologue. They also inhibited P. falciparum 3D7 cell growth in vitro. Compound 3 showed little PfDHODH inhibitory activity or cell growth inhibitory activity.

Community composition of soil bacteria nearly a decade after a fire in a tropical rainforest in East Kalimantan, Indonesia.

Soil bacterial community compositions in burnt and unburnt areas in a tropical rainforest in East Kalimantan, Indonesia, were investigated 8 and 9 years after a fire by denaturing gradient gel electrophoresis analysis targeting the 16S rRNA gene. Three study sites were set in the forest area devoid of fire damage (control), and in the lightly damaged and heavily damaged forest areas. Succession of aboveground vegetation in the two damaged areas had clearly proceeded after the fire, but the vegetation types still differed from the unburnt area at the time of this study. Community composition of total soil bacteria was similar among the three areas, and so was that of actinobacteria. However, the composition of ammonia oxidizing bacteria clearly differed depending on the presence or absence of past fire damage. These results indicate that even nearly a decade after the forest fire, impacts of the fire remained on the community composition of ammonia oxidizing bacteria, but not apparently on those of dominant bacteria and actinobacteria.

Biochemical, Metabolomic, and Genetic Analyses of Dephospho Coenzyme A Kinase Involved in Coenzyme A Biosynthesis in the Human Enteric Parasite Entamoeba histolytica.

Coenzyme A (CoA) is an essential cofactor for numerous cellular reactions in all living organisms. In the protozoan parasite Entamoeba histolytica, CoA is synthesized in a pathway consisting of four enzymes with dephospho-CoA kinase (DPCK) catalyzing the last step. However, the metabolic and physiological roles of E. histolytica DPCK remain elusive. In this study, we took biochemical, reverse genetic, and metabolomic approaches to elucidate role of DPCK in E. histolytica. The E. histolytica genome encodes two DPCK isotypes (EhDPCK1 and EhDPCK2). Epigenetic gene silencing of Ehdpck1 and Ehdpck2 caused significant reduction of DPCK activity, intracellular CoA concentrations, and also led to growth retardation in vitro, suggesting importance of DPCK for CoA synthesis and proliferation. Furthermore, metabolomic analysis showed that suppression of Ehdpck gene expression also caused decrease in the level of acetyl-CoA, and metabolites involved in amino acid, glycogen, hexosamine, nucleic acid metabolisms, chitin, and polyamine biosynthesis. The kinetic properties of E. histolytica and human DPCK showed remarkable differences, e.g., the Km values of E. histolytica and human DPCK were 58-114 and 5.2 µM toward dephospho-CoA and 15-20 and 192 µM for ATP, respectively. Phylogenetic analysis also supported the uniqueness of the amebic enzyme compared to the human counterpart. These biochemical, evolutionary features, and physiological importance of EhDPCKs indicate that EhDPCK represents the rational target for the development of anti-amebic agents.

Characterization and validation of Entamoeba histolytica pantothenate kinase as a novel anti-amebic drug target.

The Coenzyme A (CoA), as a cofactor involved in >100 metabolic reactions, is essential to the basic biochemistry of life. Here, we investigated the CoA biosynthetic pathway of Entamoeba histolytica (E. histolytica), an enteric protozoan parasite responsible for human amebiasis. We identified four key enzymes involved in the CoA pathway: pantothenate kinase (PanK, EC 2.7.1.33), bifunctional phosphopantothenate-cysteine ligase/decarboxylase (PPCS-PPCDC), phosphopantetheine adenylyltransferase (PPAT) and dephospho-CoA kinase (DPCK). Cytosolic enzyme PanK, was selected for further biochemical, genetic, and phylogenetic characterization. Since E. histolytica PanK (EhPanK) is physiologically important and sufficiently divergent from its human orthologs, this enzyme represents an attractive target for the development of novel anti-amebic chemotherapies. Epigenetic gene silencing of PanK resulted in a significant reduction of PanK activity, intracellular CoA concentrations, and growth retardation in vitro, reinforcing the importance of this gene in E. histolytica. Furthermore, we screened the Kitasato Natural Products Library for inhibitors of recombinant EhPanK, and identified 14 such compounds. One compound demonstrated moderate inhibition of PanK activity and cell growth at a low concentration, as well as differential toxicity towards E. histolytica and human cells.

Actinoplanes bogoriensis sp. nov., a novel actinomycete isolated from leaf litter.

A novel actinomycete, designated LIPI11-2-Ac043(T), was isolated from leaf litter collected in Indonesia. According to phylogenetic analysis based on the 16S rRNA gene sequence comparisons, strain LIPI11-2-Ac043(T) was closely related to Actinoplanes abujensis A4029(T) (99.3%) and Actinoplanes brasiliensis DSM 43805(T) (98.8%). Spores of strain LIPI11-2-Ac043(T) were motile and the sporangia were spherical. The predominant menaquinone was MK-9(H6) and the principal polar lipids were phosphatidylinositol, phosphatidylethanolamine, phosphatidylglycerol and diphospatidylglycerol. The whole-cell sugars were galactose, glucose and mannose; rhibose, arabinose and xylose were also detected as minor components. The major fatty acids were anteiso-C15:0, iso-C16:0, iso-C15:0 and anteiso-C17:0. These data supported the affiliation of strain LIPI11-2-Ac043(T) to the genus Actinoplanes. Meanwhile, the results of DNA-DNA hybridization and physiological and biochemical tests indicated that strain LIPI11-2-Ac043(T) can be distinguished from its closest related species. Therefore, strain LIPI11-2-Ac043(T) represents a novel species of the genus Actinoplanes, for which the name Actinoplanes bogoriensis sp. nov. is proposed. The type strain is LIPI11-2-Ac043(T) (=InaCC A522(T)=NBRC 110975(T)).