Stimulation of soluble guanylate cyclase exerts antiinflammatory actions in the liver through a VASP/NF-κB/NLRP3 inflammasome circuit.

Soluble guanylate cyclase (sGC) catalyzes the conversion of guanosine triphosphate into cyclic guanosine-3',5'-monophosphate, a key second messenger in cell signaling and tissue homeostasis. It was recently demonstrated that sGC stimulation is associated with a marked antiinflammatory effect in the liver of mice with experimental nonalcoholic steatohepatitis (NASH). Here, we investigated the mechanisms underlying the antiinflammatory effect of the sGC stimulator praliciguat (PRL) in the liver. Therapeutic administration of PRL exerted antiinflammatory and antifibrotic actions in mice with choline-deficient l-amino acid-defined high-fat diet-induced NASH. The PRL antiinflammatory effect was associated with lower F4/80- and CX3CR1-positive macrophage infiltration into the liver in parallel with lower Ly6CHigh- and higher Ly6CLow-expressing monocytes in peripheral circulation. The PRL antiinflammatory effect was also associated with suppression of hepatic levels of interleukin (IL)-1ß, NLPR3 (NACHT, LRR, and PYD domain-containing protein 3), ASC (apoptosis-associated speck-like protein containing a caspase-recruitment domain), and active cleaved-caspase-1, which are components of the NLRP3 inflammasome. In Kupffer cells challenged with the classical inflammasome model of lipopolysaccharide plus adenosine triphosphate, PRL inhibited the priming (expression of Il1b and Nlrp3) and blocked the release of mature IL-1ß. Mechanistically, PRL induced the protein kinase G (PKG)-mediated phosphorylation of the VASP (vasodilator-stimulated phosphoprotein) Ser239 residue which, in turn, reduced nuclear factor-κB (NF-κB) activity and Il1b and Nlrp3 gene transcription. PRL also reduced active cleaved-caspase-1 levels independent of pannexin-1 activity. These data indicate that sGC stimulation with PRL exerts antiinflammatory actions in the liver through mechanisms related to a PKG/VASP/NF-κB/NLRP3 inflammasome circuit.

sGC stimulator praliciguat suppresses stellate cell fibrotic transformation and inhibits fibrosis and inflammation in models of NASH.

Endothelial dysfunction and reduced nitric oxide (NO) signaling are a key element of the pathophysiology of nonalcoholic steatohepatitis (NASH). Stimulators of soluble guanylate cyclase (sGC) enhance NO signaling; have been shown preclinically to reduce inflammation, fibrosis, and steatosis; and thus have been proposed as potential therapies for NASH and fibrotic liver diseases. Praliciguat, an oral sGC stimulator with extensive distribution to the liver, was used to explore the role of this signaling pathway in NASH. We found that sGC is expressed in hepatic stellate cells and stellate-derived myofibroblasts, but not in hepatocytes. Praliciguat acted directly on isolated hepatic stellate cells to inhibit fibrotic and inflammatory signaling potentially through regulation of AMPK and SMAD7. Using in vivo microdialysis, we demonstrated stimulation of the NO-sGC pathway by praliciguat in both healthy and fibrotic livers. In preclinical models of NASH, praliciguat treatment was associated with lower levels of liver fibrosis and lower expression of fibrotic and inflammatory biomarkers. Praliciguat treatment lowered hepatic steatosis and plasma cholesterol levels. The antiinflammatory and antifibrotic effects of praliciguat were recapitulated in human microtissues in vitro. These data provide a plausible cellular basis for the mechanism of action of sGC stimulators and suggest the potential therapeutic utility of praliciguat in the treatment of NASH.

Soluble guanylate cyclase stimulator praliciguat attenuates inflammation, fibrosis, and end-organ damage in the Dahl model of cardiorenal failure.

Reduced nitric oxide (NO) and a decrease in cGMP signaling mediated by soluble guanylate cyclase (sGC) has been linked to the development of several cardiorenal diseases. Stimulation of sGC is a potential means for enhancing cGMP production in conditions of reduced NO bioavailability. The purpose of our studies was to determine the effects of praliciguat, a clinical-stage sGC stimulator, in a model of cardiorenal failure. Dahl salt-sensitive rats fed a high-salt diet to induce hypertension and organ damage were treated with the sGC stimulator praliciguat to determine its effects on hemodynamics, biomarkers of inflammation, fibrosis, tissue function, and organ damage. Praliciguat treatment reduced blood pressure, improved cardiorenal damage, and attenuated the increase in circulating markers of inflammation and fibrosis. Notably, praliciguat affected markers of renal damage at a dose that had minimal effect on blood pressure. In addition, liver fibrosis and circulating markers of tissue damage were attenuated in praliciguat-treated rats. Stimulation of the NO-sGC-cGMP pathway by praliciguat attenuated or normalized indicators of chronic inflammation, fibrosis, and tissue dysfunction in the Dahl salt-sensitive rat model. Stimulation of sGC by praliciguat may present an effective mechanism for treating diseases linked to NO deficiency, particularly those associated with cardiac and renal failure. Praliciguat is currently being evaluated in patients with diabetic nephropathy and heart failure with preserved ejection fraction.

Pharmacological Characterization of IW-1973, a Novel Soluble Guanylate Cyclase Stimulator with Extensive Tissue Distribution, Antihypertensive, Anti-Inflammatory, and Antifibrotic Effects in Preclinical Models of Disease.

Soluble guanylate cyclase (sGC), a key signal-transduction enzyme, increases the conversion of guanosine-5'-triphosphate to cGMP upon binding of nitric oxide (NO). Endothelial dysfunction and/or reduced NO signaling have been implicated in cardiovascular disease pathogenesis and complications of diabetes and have been associated with other disease states and aging. Soluble guanylate cyclase (sGC) stimulators are small-molecule drugs that bind sGC and enhance NO-mediated cGMP signaling. The pharmacological characterization of IW-1973 [1,1,1,3,3,3-hexafluoro-2-(((5-fluoro-2-(1-(2-fluorobenzyl)-5-(isoxazol-3-yl)-1H-pyrazol-3-yl) pyrimidin-4-yl)amino)methyl)propan-2-ol], a novel clinical-stage sGC stimulator under clinical investigation for treatment of heart failure with preserved ejection fraction and diabetic nephropathy, is described. In the presence of NO, IW-1973 stimulated sGC in a human purified enzyme assay and a HEK-293 whole cell assay. sGC stimulation by IW-1973 in cells was associated with increased phosphorylation of vasodilator-stimulated phosphoprotein. IW-1973, at doses of 1-10 mg/kg, significantly lowered blood pressure in normotensive and spontaneously hypertensive rats. In a Dahl salt-sensitive hypertension model, IW-1973 significantly reduced blood pressure, inflammatory cytokine levels, and renal disease markers, including proteinuria and renal fibrotic gene expression. The results were affirmed in mouse lipopolysaccharide-induced inflammation and rat unilateral ureteral obstruction renal fibrosis models. A quantitative whole-body autoradiography study of IW-1973 revealed extensive tissue distribution and pharmacokinetic studies showed a large volume of distribution and a profile consistent with predicted once-a-day dosing in humans. In summary, IW-1973 is a potent, orally available sGC stimulator that exhibits renoprotective, anti-inflammatory, and antifibrotic effects in nonclinical models.

Olinciguat, an Oral sGC Stimulator, Exhibits Diverse Pharmacology Across Preclinical Models of Cardiovascular, Metabolic, Renal, and Inflammatory Disease.

Nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic 3',5' GMP (cGMP) signaling plays a central role in regulation of diverse processes including smooth muscle relaxation, inflammation, and fibrosis. sGC is activated by the short-lived physiologic mediator NO. sGC stimulators are small-molecule compounds that directly bind to sGC to enhance NO-mediated cGMP signaling. Olinciguat, (R)-3,3,3-trifluoro-2-(((5-fluoro-2-(1-(2-fluorobenzyl)-5-(isoxazol-3-yl)-1H-pyrazol-3-yl)pyrimidin-4-yl)amino)methyl)-2-hydroxypropanamide, is a new sGC stimulator currently in Phase 2 clinical development. To understand the potential clinical utility of olinciguat, we studied its pharmacokinetics, tissue distribution, and pharmacologic effects in preclinical models. Olinciguat relaxed human vascular smooth muscle and was a potent inhibitor of vascular smooth muscle proliferation in vitro. These antiproliferative effects were potentiated by the phosphodiesterase 5 inhibitor tadalafil, which did not inhibit vascular smooth muscle proliferation on its own. Olinciguat was orally bioavailable and predominantly cleared by the liver in rats. In a rat whole body autoradiography study, olinciguat-derived radioactivity in most tissues was comparable to plasma levels, indicating a balanced distribution between vascular and extravascular compartments. Olinciguat was explored in rodent models to study its effects on the vasculature, the heart, the kidneys, metabolism, and inflammation. Olinciguat reduced blood pressure in normotensive and hypertensive rats. Olinciguat was cardioprotective in the Dahl rat salt-sensitive hypertensive heart failure model. In the rat ZSF1 model of diabetic nephropathy and metabolic syndrome, olinciguat was renoprotective and associated with lower circulating glucose, cholesterol, and triglycerides. In a mouse TNFα-induced inflammation model, olinciguat treatment was associated with lower levels of endothelial and leukocyte-derived soluble adhesion molecules. The pharmacological features of olinciguat suggest that it may have broad therapeutic potential and that it may be suited for diseases that have both vascular and extravascular pathologies.

The soluble guanylate cyclase stimulator IW-1973 prevents inflammation and fibrosis in experimental non-alcoholic steatohepatitis.

BACKGROUND AND PURPOSE: Non-alcoholic steatohepatitis (NASH) is the hepatic manifestation of metabolic syndrome and is characterized by steatosis, inflammation and fibrosis. Soluble guanylate cyclase (sGC) stimulation reduces inflammation and fibrosis in experimental models of lung, kidney and heart disease. Here, we tested whether sGC stimulation is also effective in experimental NASH. EXPERIMENTAL APPROACH: NASH was induced in mice by feeding a choline-deficient, l-amino acid-defined, high-fat diet. These mice received either placebo or the sGC stimulator IW-1973 at two different doses (1 and 3 mg·kg-1 ·day-1 ) for 9 weeks. IW-1973 was also tested in high-fat diet (HFD)-induced obese mice. Steatosis, inflammation and fibrosis were assessed by Oil Red O, haematoxylin-eosin, Masson's trichrome, Sirius Red, F4/80 and α-smooth muscle actin staining. mRNA expression was assessed by quantitative PCR. Levels of IW-1973, cytokines and cGMP were determined by LC-MS/MS, Luminex and enzyme immunoassay respectively. KEY RESULTS: Mice with NASH showed reduced cGMP levels and sGC expression, increased steatosis, inflammation, fibrosis, TNF-α and MCP-1 levels and up-regulated collagen types I α1 and α2, MMP2, TGF-ß1 and tissue metallopeptidase inhibitor 1 expression. IW-1973 restored hepatic cGMP levels and sGC expression resulting in a dose-dependent reduction of hepatic inflammation and fibrosis. IW-1973 levels were ≈40-fold higher in liver tissue than in plasma. IW-1973 also reduced hepatic steatosis and adipocyte hypertrophy secondary to enhanced autophagy in HFD-induced obese mice. CONCLUSIONS AND IMPLICATIONS: Our data indicate that sGC stimulation prevents hepatic steatosis, inflammation and fibrosis in experimental NASH. These findings warrant further evaluation of IW-1973 in the clinical setting.

The Soluble Guanylate Cyclase Stimulator IWP-953 Increases Conventional Outflow Facility in Mouse Eyes.

PURPOSE: The nitric oxide (NO)-cyclic guanosine-3',5'-monophosphate (cGMP) pathway regulates aqueous humor outflow and therefore, intraocular pressure. We investigated the pharmacologic effects of the soluble guanylate cyclase (sGC) stimulator IWP-953 on primary human trabecular meshwork (HTM) cells and conventional outflow facility in mouse eyes. METHODS: Cyclic GMP levels were determined in vitro in HEK-293 cells and four HTM cell strains (HTM120/HTM123: predominantly myofibroblast-like phenotype, HTM130/HTM141: predominantly endothelial-like phenotype), and in HTM cell culture supernatants. Conventional outflow facility was measured following intracameral injection of IWP-953 or DETA-NO using a computerized pressure-controlled perfusion system in enucleated mouse eyes ex vivo. RESULTS: IWP-953 markedly stimulated cGMP production in HEK-293 cells in the presence and absence of DETA-NO (half maximal effective concentrations: 17 nM, 9.5 µM). Similarly, IWP-953 stimulated cGMP production in myofibroblast-like HTM120 and HTM123 cells, an effect that was greatly amplified by the presence of DETA-NO. In contrast, IWP-953 stimulation of cGMP production in endothelial-like HTM130 and HTM141 cells was observed, but was markedly less prominent than in HTM120 and HTM123 cells. Notably, cGMP was found in all HTM culture supernatants, following IWP-953/DETA-NO stimulation. In paired enucleated mouse eyes, IWP-953 at 10, 30, 60, and 100 µM concentration-dependently increased outflow facility. This effect (89.5%) was maximal at 100 µM (P = 0.002) and in magnitude comparable to DETA-NO at 100 µM (97.5% increase, P = 0.030). CONCLUSIONS: These data indicate that IWP-953, via modulation of the sGC-cGMP pathway, increases aqueous outflow facility in mouse eyes, suggesting therapeutic potential for sGC stimulators as novel ocular hypotensive drugs.

Discovery of IWP-051, a Novel Orally Bioavailable sGC Stimulator with Once-Daily Dosing Potential in Humans.

In recent years, soluble guanylate cyclase (sGC, EC 4.6.1.2) has emerged as an attractive therapeutic target for treating cardiovascular diseases and diseases associated with fibrosis and end-organ failure. Herein, we describe our design and synthesis of a series of 4-hydroxypyrimidine sGC stimulators starting with an internally discovered lead. Our efforts have led to the discovery of IWP-051, a molecule that achieves good alignment of potency, stability, selectivity, and pharmacodynamic effects while maintaining favorable pharmacokinetic properties with once-daily dosing potential in humans.

Electrical and mechanical recovery of cardiac function following out-of-hospital cardiac arrest.

BACKGROUND: Compression pauses may be particularly harmful following the electrical recovery but prior to the mechanical recovery from cardiopulmonary arrest. METHODS AND RESULTS: A convenience sample of patients with out-of-hospital cardiac arrest (OOHCA) were identified. Data were exported from defibrillators to define compression pauses, electrocardiogram rhythm, PetCO2, and the presence of palpable pulses. Pulse-check episodes were randomly assigned to a derivation set (one-third) and a validation set (two-thirds). Both an unweighted and a weighted receiver-operator curve (ROC) analysis were performed on the derivation set to identify optimal thresholds to predict ROSC using heart rate and PetCO2. A sequential decision guideline was generated to predict the presence of ROSC during compressions and confirm perfusion once compressions were stopped. The ability of this decision guideline to correctly identify pauses in which pulses were and were not palpated was then evaluated. A total of 145 patients with 349 compression pauses were included. The ROC analyses on the derivation set identified an optimal pre-pause heart rate threshold of >40 beats min(-1) and an optimal PetCO2 threshold of >20 mmHg to predict ROSC. A sequential decision guideline was developed using pre-pause heart rate and PetCO2 as well as the PetCO2 pattern during compression pauses to predict and rapidly confirm ROSC. This decision guideline demonstrated excellent predictive ability to identifying compression pauses with and without palpable pulses (positive predictive value 95%, negative predictive value 99%). The mean latency period between recovery of electrical and mechanical cardiac function was 78 s (95% CI 36-120 s). CONCLUSIONS: Heart rate and PetCO2 can predict ROSC without stopping compressions, and the PetCO2 pattern during compression pauses can rapidly confirm ROSC. Use of a sequential decision guideline using heart rate and PetCO2 may reduce unnecessary compression pauses during critical moments during recovery from cardiopulmonary arrest.

Minimizing pre- and post-defibrillation pauses increases the likelihood of return of spontaneous circulation (ROSC).

BACKGROUND: The three-phase model of ventricular fibrillation (VF) arrest suggests a period of compressions to "prime" the heart prior to defibrillation attempts. In addition, post-shock compressions may increase the likelihood of return of spontaneous circulation (ROSC). The optimal intervals for shock delivery following cessation of compressions (pre-shock interval) and resumption of compressions following a shock (post-shock interval) remain unclear. OBJECTIVE: To define optimal pre- and post-defibrillation compression pauses for out-of-hospital cardiac arrest (OOHCA). METHODS: All patients suffering OOHCA from VF were identified over a 1-month period. Defibrillator data were abstracted and analyzed using the combination of ECG, impedance, and audio recording. Receiver-operator curve (ROC) analysis was used to define the optimal pre- and post-shock compression intervals. Multiple logistic regression analysis was used to quantify the relationship between these intervals and ROSC. Covariates included cumulative number of defibrillation attempts, intubation status, and administration of epinephrine in the immediate pre-shock compression cycle. Cluster adjustment was performed due to the possibility of multiple defibrillation attempts for each patient. RESULTS: A total of 36 patients with 96 defibrillation attempts were included. The ROC analysis identified an optimal pre-shock interval of <3s and an optimal post-shock interval of <6s. Increased likelihood of ROSC was observed with a pre-shock interval <3s (adjusted OR 6.7, 95% CI 2.0-22.3, p=0.002) and a post-shock interval of <6s (adjusted OR 10.7, 95% CI 2.8-41.4, p=0.001). Likelihood of ROSC was substantially increased with the optimization of both pre- and post-shock intervals (adjusted OR 13.1, 95% CI 3.4-49.9, p<0.001). CONCLUSIONS: Decreasing pre- and post-shock compression intervals increases the likelihood of ROSC in OOHCA from VF.

Clinical array comparative genomic hybridization: a new paradigm.

BACKGROUND: Although the clinical utility of array comparative genomic hybridization (aCGH) is undisputed, the implementation of this technology is a unique experience for each laboratory. OBJECTIVE: Endeavors to construct a bacterial artificial chromosome (BAC)-based CGH microarray targeting microdeletion and duplication syndromes related to mental retardation and developmental delay are described. METHOD: Covering each chromosome at the 650-band level, the array comprises 1360 BAC clones with emphasis on the subtelomeric and pericentromeric regions and enrichment of genomic hot spots containing genes associated with specific constitutional disorders. During development of the array, fluorescence in situ hybridization (FISH) and end-sequencing analysis eliminated 24% of BACs that were mismapped or cross-hybridized, underscoring the need rigorously to assess arrayed elements. Performance of the BACs was tested further with chromosome-specific add-in experiments. CONCLUSION: Of the first 500 clinical cases, 54 (11%) showed chromosome abnormalities, which were confirmed by FISH with BACs from the aberrant loci or by conventional cytogenetics. Array CGH is a powerful tool that is now being implemented in the realm of diagnostic testing.

Klebsiella pneumoniae multiresistance plasmid pMET1: similarity with the Yersinia pestis plasmid pCRY and integrative conjugative elements.

BACKGROUND: Dissemination of antimicrobial resistance genes has become an important public health and biodefense threat. Plasmids are important contributors to the rapid acquisition of antibiotic resistance by pathogenic bacteria. PRINCIPAL FINDINGS: The nucleotide sequence of the Klebsiella pneumoniae multiresistance plasmid pMET1 comprises 41,723 bp and includes Tn1331.2, a transposon that carries the bla(TEM-1) gene and a perfect duplication of a 3-kbp region including the aac(6')-Ib, aadA1, and bla(OXA-9) genes. The replication region of pMET1 has been identified. Replication is independent of DNA polymerase I, and the replication region is highly related to that of the cryptic Yersinia pestis 91001 plasmid pCRY. The potential partition region has the general organization known as the parFG locus. The self-transmissible pMET1 plasmid includes a type IV secretion system consisting of proteins that make up the mating pair formation complex (Mpf) and the DNA transfer (Dtr) system. The Mpf is highly related to those in the plasmid pCRY, the mobilizable high-pathogenicity island from E. coli ECOR31 (HPI(ECOR31)), which has been proposed to be an integrative conjugative element (ICE) progenitor of high-pathogenicity islands in other Enterobacteriaceae including Yersinia species, and ICE(Kp1), an ICE found in a K. pneumoniae strain causing primary liver abscess. The Dtr MobB and MobC proteins are highly related to those of pCRY, but the endonuclease is related to that of plasmid pK245 and has no significant homology with the protein of similar function in pCRY. The region upstream of mobB includes the putative oriT and shares 90% identity with the same region in the HPI(ECOR31). CONCLUSIONS: The comparative analyses of pMET1 with pCRY, HPI(ECOR31), and ICE(Kp1 )show a very active rate of genetic exchanges between Enterobacteriaceae including Yersinia species, which represents a high public health and biodefense threat due to transfer of multiple resistance genes to pathogenic Yersinia strains.

External guide sequences targeting the aac(6')-Ib mRNA induce inhibition of amikacin resistance.

The dissemination of AAC(6')-I-type acetyltransferases have rendered amikacin and other aminoglycosides all but useless in some parts of the world. Antisense technologies could be an alternative to extend the life of these antibiotics. External guide sequences are short antisense oligoribonucleotides that induce RNase P-mediated cleavage of a target RNA by forming a precursor tRNA-like complex. Thirteen-nucleotide external guide sequences complementary to locations within five regions accessible for interaction with antisense oligonucleotides in the mRNA that encodes AAC(6')-Ib were analyzed. While small variations in the location targeted by different external guide sequences resulted in big changes in efficiency of binding to native aac(6')-Ib mRNA, most of them induced high levels of RNase P-mediated cleavage in vitro. Recombinant plasmids coding for selected external guide sequences were introduced into Escherichia coli harboring aac(6')-Ib, and the transformant strains were tested to determine their resistance to amikacin. The two external guide sequences that showed the strongest binding efficiency to the mRNA in vitro, EGSC3 and EGSA2, interfered with expression of the resistance phenotype at different degrees. Growth curve experiments showed that E. coli cells harboring a plasmid coding for EGSC3, the external guide sequence with the highest mRNA binding affinity in vitro, did not grow for at least 300 min in the presence of 15 mug of amikacin/ml. EGSA2, which had a lower mRNA-binding affinity in vitro than EGSC3, inhibited the expression of amikacin resistance at a lesser level; growth of E. coli harboring a plasmid coding for EGSA2, in the presence of 15 mug of amikacin/ml was undetectable for 200 min but reached an optical density at 600 nm of 0.5 after 5 h of incubation. Our results indicate that the use of external guide sequences could be a viable strategy to preserve the efficacy of amikacin.

Inhibition of aminoglycoside 6'-N-acetyltransferase type Ib-mediated amikacin resistance by antisense oligodeoxynucleotides.

Amikacin has been very useful in the treatment of infections caused by multiresistant bacteria because it is refractory to the actions of most modifying enzymes. However, the spread of AAC(6')-I-type acetyltransferases, enzymes capable of catalyzing inactivation of amikacin, has rendered this antibiotic all but useless in some parts of the world. The aminoglycoside 6'-N-acetyltransferase type Ib, which is coded for by the aac(6')-Ib gene, mediates resistance to amikacin and other aminoglycosides. RNase H mapping and computer prediction of the secondary structure led to the identification of five regions accessible for interaction with antisense oligodeoxynucleotides in the aac(6')-Ib mRNA. Oligodeoxynucleotides targeting these regions could bind to native mRNA with different efficiencies and mediated RNase H digestion. Selected oligodeoxynucleotides inhibited AAC(6')-Ib synthesis in cell-free coupled transcription-translation assays. After their introduction into an Escherichia coli strain harboring aac(6')-Ib by electroporation, some of these oligodeoxynucleotides decreased the level of resistance to amikacin. Our results indicate that use of antisense compounds could be a viable strategy to preserve the efficacies of existing antibiotics to which bacteria are becoming increasingly resistant.

Complete nucleotide sequence of Klebsiella pneumoniae multiresistance plasmid pJHCMW1.

The multiresistance plasmid pJHCMW1, harbored by a clinical Klebsiella pneumoniae strain isolated from a neonate with meningitis, was sequenced. A circular sequence of 11,354 bp was generated, of which 7,993 bp make up Tn1331, a transposon including the antibiotic resistance genes aac(6')-Ib, aadA1, bla(OXA-9), and bla(TEM-1). The gene aac(6')-Ib is included in a gene cassette, and both aadA1 and bla(OXA-9) are included in a single-gene cassette that may have arisen as a consequence of a recombination event involving two integrons. The pJHCMW1 plasmid replicates through a ColE1-like RNA-regulated mechanism, includes a functional oriT, and two loci with similarity to XerCD site-specific recombination target sites involved in plasmid stabilization by the resolution of multimers. One of these two loci, mwr, is active and has been the subject of previous studies, and the other, dxs, is not functional but binds the recombinase XerD with low affinity. Two additional open reading frames were identified, one with low similarity to two hypothetical membrane proteins from Mycobacterium tuberculosis and Mycobacterium leprae and the other with low similarity to psiB, a gene encoding a function that facilitates the establishment of the transferring plasmid in the recipient bacterial cell during the process of conjugation.