Septal Localization of the Mycobacterium tuberculosis MtrB Sensor Kinase Promotes MtrA Regulon Expression

Plocinska, Renata; Gorla, Purushotham; Sarva, Krishna; Vadrevu, Indumathi S.; Paul, Pandeeti Emmanuel Vijay; Arora, Neelima; Płociński, Przemysław; Madiraju, Murty V. V. S.; Rajagopalan, Malini

doi:10.1074/jbc.m112.346544

Cited by 65 publications

(110 citation statements)

References 49 publications

(72 reference statements)

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“…CwsA also contains a single TM helix. A crgA and cwsA double-deletion mutant showed the importance of the corresponding gene products for cell wall synthesis and cell shape maintenance (8).…”

Section: Significancementioning

confidence: 99%

Structure of CrgA, a cell division structural and regulatory protein fromMycobacterium tuberculosis, in lipid bilayers

Das

Dai

Hung

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The 93-residue transmembrane protein CrgA in Mycobacterium tuberculosis is a central component of the divisome, a large macromolecular machine responsible for cell division. Through interactions with multiple other components including FtsZ, FtsQ, FtsI (PBPB), PBPA, and CwsA, CrgA facilitates the recruitment of the proteins essential for peptidoglycan synthesis to the divisome and stabilizes the divisome. CrgA is predicted to have two transmembrane helices. Here, the structure of CrgA was determined in a liquid–crystalline lipid bilayer environment by solid-state NMR spectroscopy. Oriented-sample data yielded orientational restraints, whereas magic-angle spinning data yielded interhelical distance restraints. These data define a complete structure for the transmembrane domain and provide rich information on the conformational ensembles of the partially disordered N-terminal region and interhelical loop. The structure of the transmembrane domain was refined using restrained molecular dynamics simulations in an all-atom representation of the same lipid bilayer environment as in the NMR samples. The two transmembrane helices form a left-handed packing arrangement with a crossing angle of 24° at the conserved Gly39 residue. This helix pair exposes other conserved glycine and alanine residues to the fatty acyl environment, which are potential sites for binding CrgA’s partners such as CwsA and FtsQ. This approach combining oriented-sample and magic-angle spinning NMR spectroscopy in native-like lipid bilayers with restrained molecular dynamics simulations represents a powerful tool for structural characterization of not only isolated membrane proteins, but their complexes, such as those that form macromolecular machines.

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Section: Significancementioning

confidence: 99%

Structure of CrgA, a cell division structural and regulatory protein fromMycobacterium tuberculosis, in lipid bilayers

Das

Dai

Hung

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…S1 in the supplemental material). Presumably, the diffuse and weak fluorescence was due to paraformaldehyde fixation, a safety step used prior to visualization of structures in M. tuberculosis; paraformaldehyde fixation is known to quench the fluorescence intensity of some cell division proteins (28,29). We also examined GFP-CwsA localization in the M. smegmatis crgA mutant background.…”

Section: Resultsmentioning

confidence: 99%

“…RipA, an essential cell wall hydrolase and a target of the MtrA response regulator (28), interacts with RpfB, a lytic transglycosylase and one of the five resuscitation-promoting factors in M. tuberculosis. The RipARpfB-mediated synergistic hydrolysis of PG is modulated by PBP 1 (16,17).…”

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confidence: 99%

Mycobacterium tuberculosis CwsA Interacts with CrgA and Wag31, and the CrgA-CwsA Complex Is Involved in Peptidoglycan Synthesis and Cell Shape Determination

et al. 2012

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cBacterial cell division and cell wall synthesis are highly coordinated processes involving multiple proteins. Here, we show that Rv0008c, a novel small membrane protein from Mycobacterium tuberculosis, localizes to the poles and on membranes and shows an overall punctate localization throughout the cell. Furthermore, Rv0008c interacts with two proteins, CrgA and Wag31, implicated in peptidoglycan (PG) synthesis in mycobacteria. Deletion of the Rv0008c homolog in M. smegmatis, MSMEG_0023, caused bulged cell poles, formation of rounded cells, and defects in polar localization of Wag31 and cell wall synthesis, with cell wall synthesis measured by the incorporation of the [ 14 C]N-acetylglucosamine cell wall precursor. The M. smegmatis MSMEG_0023 crgA double mutant strain showed severe defects in growth, viability, cell wall synthesis, cell shape, and the localization of the FtsZ, FtsI, and Wag31 proteins. The double mutant strain also exhibited increased autolytic activity in the presence of detergents. Because CrgA and Wag31 proteins interact with FtsI individually, we believe that regulated cell wall synthesis and cell shape maintenance require the concerted actions of the CrgA, Rv0008c, FtsI, and Wag31 proteins. We propose that, together, CrgA and Rv0008c, renamed CwsA for cell wall synthesis and cell shape protein A, play crucial roles in septal and polar PG synthesis and help coordinate these processes with the FtsZ-ring assembly in mycobacteria. Since its reemergence in the early 1990s, tuberculosis caused by Mycobacterium tuberculosis remains a leading cause of global morbidity and mortality. With nearly 10 million new cases reported each year and 2 billion people infected, as well as the emergence of extensively drug-resistant and completely drug-resistant strains, sustained interest in improved control measures and tuberculosis research is crucial (4, 40). These reports emphasize the importance of understanding the basic biology of the pathways needed for pathogen proliferation, namely, DNA replication and cell division, and the development of novel strategies for combating M. tuberculosis infection (27).Cell division in bacteria is accomplished by the coordinated actions of multiple proteins that form a septal ring in the middle of a dividing cell. FtsZ, a cytoskeletal protein and a GTPase, initiates the cytokinesis process by the GTP-dependent midcell assembly of a ring structure called the Z ring (2). Constriction of the Z ring, driven by the GTPase activity of FtsZ, initiates cell division. During various stages of cell division, FtsZ interacts with a number of proteins, and these interactions modulate its midcell localization, membrane tethering, biochemical activities, and influence on the assembly of other septal ring members, including some proteins involved in peptidoglycan (PG) synthesis (reviewed in reference 2). Recent data also suggest that, at least in some bacteria, FtsZ plays a role in guiding cell wall synthesis (1, 37).In the last decade, significant advancements have been made not only ...

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“…Two TCSs in M. tuberculosis, MtrAB (80) and PrrAB (81), are essential for growth under unstressed culture conditions and have been integrated into the basic physiology of the bacteria. The HK MtrB colocalizes with cell division machinery at the bacterial septa and poles (82). Upon stimulation by an unknown signal, MtrB phosphorylates its cognate RR MtrA, which then binds DNA and activates transcription of a regulon that includes essential replication and cell division genes dnaA and ripA as well as the fbpB and rpfB genes that encode proteins with roles during infection (82)(83)(84).…”

Section: Essential Tcss and Tfs-always On The Lookout For Hostilitymentioning

confidence: 99%

“…The HK MtrB colocalizes with cell division machinery at the bacterial septa and poles (82). Upon stimulation by an unknown signal, MtrB phosphorylates its cognate RR MtrA, which then binds DNA and activates transcription of a regulon that includes essential replication and cell division genes dnaA and ripA as well as the fbpB and rpfB genes that encode proteins with roles during infection (82)(83)(84). Integration of a TCS with the cell division machinery could allow these slowly replicating bacteria to sense environmental stress and abort cell division if unfavorable conditions surface.…”

Section: Essential Tcss and Tfs-always On The Lookout For Hostilitymentioning

confidence: 99%

Mycobacterium tuberculosis Transcription Machinery: Ready To Respond to Host Attacks

2016

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Regulating responses to stress is critical for all bacteria, whether they are environmental, commensal, or pathogenic species. For pathogenic bacteria, successful colonization and survival in the host are dependent on adaptation to diverse conditions imposed by the host tissue architecture and the immune response. Once the bacterium senses a hostile environment, it must enact a change in physiology that contributes to the organism's survival strategy. Inappropriate responses have consequences; hence, the execution of the appropriate response is essential for survival of the bacterium in its niche. Stress responses are most often regulated at the level of gene expression and, more specifically, transcription. This minireview focuses on mechanisms of regulating transcription initiation that are required by Mycobacterium tuberculosis to respond to the arsenal of defenses imposed by the host during infection. In particular, we highlight how certain features of M. tuberculosis physiology allow this pathogen to respond swiftly and effectively to host defenses. By enacting highly integrated and coordinated gene expression changes in response to stress, M. tuberculosis is prepared for battle against the host defense and able to persist within the human population.T he survival of any organism relies on its ability to sense and respond to changes in its environment. For bacteria, stress responses are primarily mediated through the regulation of gene expression. By integrating multiple molecular approaches to gene regulation, pathogenic bacteria are able to orchestrate conditionspecific patterns that promote survival and pathogenesis in the face of a strong immune response. This minireview focuses on mechanisms of transcription regulation required for stress responses in one of the most successful and deadly pathogens in the world, Mycobacterium tuberculosis. M. tuberculosis has coexisted with humans for Ͼ50,000 years (1) and continues to cause more than 1.5 million deaths a year (2). The coevolution of M. tuberculosis with the human host response to infection has resulted in a pathogen that is specialized for long-term infection in people. Tuberculosis is a complex disease that requires the bacteria to multiply within phagocytes, survive extracellularly in hypoxic and necrotic granulomas, and endure a robust immune response to persist in the host. During infection, the host immune response restrains M. tuberculosis from proliferating by imposing a battery of defenses, including reactive oxygen and nitrogen stress, hypoxia, acid stress, genotoxic stress, cell surface stress, and starvation (3). Despite this onslaught of attacks, M. tuberculosis is able to persist for the lifetime of the host, indicating that this pathogen has highly effective molecular mechanisms to resist host-inflicted damage. In order to enact these defenses and facilitate this specialized lifestyle, M. tuberculosis executes a complex, interconnected web of stress responses that rely on changes in gene expression. In fact, M. tuberculosis is well suite...

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Septal Localization of the Mycobacterium tuberculosis MtrB Sensor Kinase Promotes MtrA Regulon Expression

Cited by 65 publications

References 49 publications

Structure of CrgA, a cell division structural and regulatory protein fromMycobacterium tuberculosis, in lipid bilayers

Structure of CrgA, a cell division structural and regulatory protein fromMycobacterium tuberculosis, in lipid bilayers

Mycobacterium tuberculosis CwsA Interacts with CrgA and Wag31, and the CrgA-CwsA Complex Is Involved in Peptidoglycan Synthesis and Cell Shape Determination

Mycobacterium tuberculosis Transcription Machinery: Ready To Respond to Host Attacks

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