Piercehansen5211

Phase variation in NanH3 may be involved in immune evasion or modulation of adhesion to host epithelial cells and formation of biofilms characteristic of the vaginal dysbiosis known as bacterial vaginosis.Atypical enteropathogenic Escherichia coli (aEPEC) are associated with diarrhea worldwide, yet genome-wide investigations to probe their virulome are lacking. In this issue of Infection and Immunity, V. E. Watson, T. H. Hazen, D. A. Rasko, M. E. Jacob, et al. (IAI 89e00619-20, 2020, https//doi.org/10.1128/IAI.00619-20) sequenced aEPEC isolates from diarrheic and asymptomatic kittens. Using phylogenomics, they demonstrated that these isolates were genetically indistinguishable from human isolates, suggesting that kittens may serve as a reservoir and, perhaps, a much-needed model to interrogate aEPEC virulence. The diarrheic isolates were hypermotile, suggesting that this phenotype may distinguish virulent strains from their innocuous counterparts.The ability of bacteria to synthesise complex polysaccharide chains at a controlled number of repeating units has wide implications for a range of biological activities that include symbiosis, biofilm formation and immune system avoidance. Complex polysaccharide chains such as the O antigen (Oag) component of lipopolysaccharide and the enterobacterial common antigen (ECA) are synthesised by the most common polysaccharide synthesis pathway used in bacteria, known as the Wzy-dependent pathway. The Oag and ECA are polymerized into chains via the inner membrane proteins WzyB and WzyE, respectively, while the respective co-polymerases WzzB and WzzE modulate the number of repeat units in the chains or "the modal length" of the polysaccharide via a hypothesised interaction. Our data shows for the first time "cross-talk" between Oag and ECA synthesis in that WzzE is able to partially regulate Oag modal length via a potential interaction with WzyB. To investigate this, one or both of the transmembrane regions (TM1 andtly synthesised by their own independent Wzy-dependent pathway. Our data show for the first time "cross-talk" between Oag and ECA synthesis and identifies novel physical protein-protein interactions between proteins in these systems. These findings further the understanding of how the system functions to control polysaccharide chain length which has great implications for novel biotechnologies and/or the combat of bacterial diseases.The cell surface of the Gram-negative cell envelope contains lipopolysaccharide (LPS) molecules, which form a permeability barrier against hydrophobic antibiotics. The LPS transport (Lpt) machine composed of LptB2FGCADE forms a proteinaceous trans-envelope bridge that allows for the rapid and specific transport of newly synthesized LPS from the inner membrane (IM) to the outer membrane (OM). This transport is powered from the IM by the ATP-binding cassette transporter LptB2FGC. AS601245 The ATP-driven cycling between closed- and open-dimer states of the ATPase LptB2 is coupled to the extraction of LPS by the transmembrane domains LptFG. However, the mechanism by which LPS moves from a substrate-binding cavity formed by LptFG at the IM to the first component of the periplasmic bridge, the periplasmic β-jellyroll domain of LptF, is poorly understood. To better understand how LptB2FGC functions in Escherichia coli, we searched for suppressors of a defective LptB variant. We found that defects in LptB2 can be suppressed b machine is powered by the cytoplasmic LptB ATPase through a poorly understood mechanism. Using genetic analyses in Escherichia coli, we found that LPS transport involves long-ranging bi-directional coupling across cellular compartments between cytoplasmic LptB and periplasmic regions of the Lpt transporter. This knowledge could be exploited in developing antimicrobials that overcome the permeability barrier imposed by LPS.The ability of Escherichia coli to grow on L-lactate as a sole carbon source depends on the expression of the lldPRD operon. A striking feature of this operon is that the transcriptional regulator (LldR) encoding gene is located between the permease (LldP) and the dehydrogenase (LldD) encoding genes. In this study we report that dosage of the LldP, LldR, and LldD proteins is not modulated on the transcriptional level. Instead, modulation of protein dosage is primarily correlated with RNase E-dependent mRNA processing events that take place within the lldR mRNA, leading to the immediate inactivation of lldR, to differential segmental stabilities of the resulting cleavage products, and to differences in the translation efficiencies of the three cistrons. A model for the processing events controlling the molar quantities of the proteins in the lldPRD operon is presented and discussed.ImportanceAdjustment of gene expression is critical for proper cell function. For the case of polycistronic transcripts, posttranscriptional regulatory mechanisms can be used to fine-tune the expression of individual cistrons. Here, we elucidate how protein dosage of the Escherichia coli lldPRD operon, which presents the paradox of having the gene encoding a regulator protein located between genes that code for a permease and an enzyme, is regulated. Our results demonstrate that the key event in this regulatory mechanism involves the RNase E-dependent cleavage of the primary lldPRD transcript at internal site(s) located within the lldR cistron, resulting in a drastic decrease of intact lldR mRNA, to differential segmental stabilities of the resulting cleavage products, and to differences in the translation efficiencies of the three cistrons.The recalcitrance of mycobacteria to antibiotic therapy is in part due to its ability to build proteins into a multi-layer cell wall. Proper synthesis of both cell wall constituents and associated proteins is crucial to maintaining cell integrity, and intimately tied to antibiotic susceptibility. How mycobacteria properly synthesize the membrane-associated proteome, however, remains poorly understood. Recently, we found that loss of lepA in Mycobacterium smegmatis (Msm) altered tolerance to rifampin, a drug that targets a non-ribosomal cellular process. LepA is a ribosome-associated GTPase found in bacteria, mitochondria, and chloroplasts, yet its physiological contribution to cellular processes is not clear. To uncover the determinants of LepA-mediated drug tolerance, we characterized the whole-cell proteomes and transcriptomes of a lepA deletion mutant relative to strains with lepA We find that LepA is important for the steady-state abundance of a number of membrane-associated proteins, including an outer membrane porin, MspA, which is integral to nutrient uptake and drug susceptibility.