Dataset Information

Conformational coupling between the active site and residues within the K(C)-channel of the Vibrio cholerae cbb3-type (C-family) oxygen reductase.

ABSTRACT: The respiratory chains of nearly all aerobic organisms are terminated by proton-pumping heme-copper oxygen reductases (HCOs). Previous studies have established that C-family HCOs contain a single channel for uptake from the bacterial cytoplasm of all chemical and pumped protons, and that the entrance of the K(C)-channel is a conserved glutamate in subunit III. However, the majority of the K(C)-channel is within subunit I, and the pathway from this conserved glutamate to subunit I is not evident. In the present study, molecular dynamics simulations were used to characterize a chain of water molecules leading from the cytoplasmic solution, passing the conserved glutamate in subunit III and extending into subunit I. Formation of the water chain, which controls the delivery of protons to the K(C)-channel, was found to depend on the conformation of Y241(Vc), located in subunit I at the interface with subunit III. Mutations of Y241(Vc) (to A/F/H/S) in the Vibrio cholerae cbb3 eliminate catalytic activity, but also cause perturbations that propagate over a 28-Å distance to the active site heme b3. The data suggest a linkage between residues lining the K(C)-channel and the active site of the enzyme, possibly mediated by transmembrane helix ?7, which contains both Y241(Vc) and the active site cross-linked Y255(Vc), as well as two CuB histidine ligands. Other mutations of residues within or near helix ?7 also perturb the active site, indicating that this helix is involved in modulation of the active site of the enzyme.

SUBMITTER: Ahn YO

PROVIDER: S-EPMC4210324 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Conformational coupling between the active site and residues within the K(C)-channel of the Vibrio cholerae cbb3-type (C-family) oxygen reductase.

Ahn Young O YO Mahinthichaichan Paween P Lee Hyun Ju HJ Ouyang Hanlin H Kaluka Daniel D Yeh Syun-Ru SR Arjona Davinia D Rousseau Denis L DL Tajkhorshid Emad E Adelroth Pia P Gennis Robert B RB

Proceedings of the National Academy of Sciences of the United States of America 20141006 42

The respiratory chains of nearly all aerobic organisms are terminated by proton-pumping heme-copper oxygen reductases (HCOs). Previous studies have established that C-family HCOs contain a single channel for uptake from the bacterial cytoplasm of all chemical and pumped protons, and that the entrance of the K(C)-channel is a conserved glutamate in subunit III. However, the majority of the K(C)-channel is within subunit I, and the pathway from this conserved glutamate to subunit I is not evident. ...[more]

PMID: 25288772

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Project description:During infection, the rates of pathogen replication, death, and migration affect disease progression, dissemination, transmission, and resistance evolution. Here, we follow the population dynamics of Vibrio cholerae in a mouse model by labeling individual bacteria with one of >500 unique, fitness-neutral genomic tags. Using the changes in tag frequencies and CFU numbers, we inform a mathematical model that describes the within-host spatiotemporal bacterial dynamics. This allows us to disentangle growth, death, forward, and retrograde migration rates continuously during infection. Our model has robust predictive power across various experimental setups. The population dynamics of V. cholerae shows substantial spatiotemporal heterogeneity in replication, death, and migration. Importantly, we find that the niche available to V. cholerae in the host increases with inoculum size, suggesting cooperative effects during infection. Therefore, it is not enough to consider just the likelihood of exposure (50% infectious dose) but rather the magnitude of exposure to predict outbreaks. IMPORTANCE Determining the rates of bacterial migration, replication, and death during infection is important for understanding how infections progress. Separately measuring these rates is often difficult in systems where multiple processes happen simultaneously. Here, we use next-generation sequencing to measure V. cholerae migration, replication, death, and niche size along the mouse gastrointestinal tract. We show that the small intestine of the mouse is a heterogeneous environment, and the population dynamic characteristics change substantially between adjacent gut sections. Our approach also allows us to characterize the effect of inoculum size on these processes. We find that the niche size in mice increases with the infectious dose, hinting at cooperative effects in larger inocula. The dose-response relationship between inoculum size and final pathogen burden is important for the infected individual and is thought to influence the progression of V. cholerae epidemics.

Dataset Information

Conformational coupling between the active site and residues within the K(C)-channel of the Vibrio cholerae cbb3-type (C-family) oxygen reductase.

Publications

Conformational coupling between the active site and residues within the K(C)-channel of the Vibrio cholerae cbb3-type (C-family) oxygen reductase.

Similar Datasets

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