The stress‐responsive chaperone α‐crystallin 2 is required for pathogenesis of <i>Mycobacterium tuberculosis</i>

Stewart, Graham R.; Newton, Sandra M.; Wilkinson, Katalin A.; Humphreys, Ian R.; Murphy, Helen N.; Robertson, Brian D.; Wilkinson, Robert J.; Young, Douglas

doi:10.1111/j.1365-2958.2004.04450.x

Cited by 76 publications

(73 citation statements)

References 40 publications

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“…During heat shock, HspR is destabilized and expression of these targets is induced. DnaK and ClpB are well-characterized protein-disaggregating chaperones (15,16) that are essential in M. tuberculosis under normal growth conditions (17), and Hsp/Acr2 is an alpha-crystallin family small heat shock protein (18)(19)(20) that may enhance the disaggregation efficiency of DnaK and ClpB (21). Thus, we hypothesized that loss of HspR function resulted in increased expression of these protein quality control genes to rescue the slow growth phenotype in our suppressor mutants.…”

Section: Resultsmentioning

confidence: 99%

Loss-of-Function Mutations in HspR Rescue the Growth Defect of a Mycobacterium tuberculosis Proteasome Accessory Factor E ( pafE ) Mutant

et al. 2017

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Mycobacterium tuberculosis uses a proteasome to degrade proteins by both ATP-dependent and -independent pathways. While much has been learned about ATP-dependent degradation, relatively little is understood about the ATPindependent pathway, which is controlled by Mycobacterium tuberculosis proteasome accessory factor E (PafE). Recently, we found that a Mycobacterium tuberculosis pafE mutant has slowed growth in vitro and is sensitive to killing by heat stress. However, we did not know if these phenotypes were caused by an inability to degrade the PafE-proteasome substrate HspR (heat shock protein repressor), an inability to degrade any damaged or misfolded proteins, or a defect in another protein quality control pathway. To address this question, we characterized pafE suppressor mutants that grew similarly to pafE ϩ bacteria under normal culture conditions. All but one suppressor mutant analyzed contained mutations that inactivated HspR function, demonstrating that the slowed growth and heat shock sensitivity of a pafE mutant were caused primarily by the inability of the proteasome to degrade HspR.IMPORTANCE Mycobacterium tuberculosis encodes a proteasome that is highly similar to eukaryotic proteasomes and is required for virulence. We recently discovered a proteasome cofactor, PafE, which is required for the normal growth, heat shock resistance, and full virulence of M. tuberculosis. In this study, we demonstrate that PafE influences this phenotype primarily by promoting the expression of protein chaperone genes that are necessary for surviving proteotoxic stress.

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Section: Resultsmentioning

confidence: 99%

Loss-of-Function Mutations in HspR Rescue the Growth Defect of a Mycobacterium tuberculosis Proteasome Accessory Factor E ( pafE ) Mutant

et al. 2017

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“…Apart from the dnaKJE-hspR operon, the expression of several other genes of M. tuberculosis is controlled by HspR. One such gene which expresses the ␣-crystallin family protein Acr2 is required for pathogenesis (24). HspR therefore appears to play a key role in controlling the expression of several M. tuberculosis genes linked to pathogenesis.…”

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confidence: 99%

DnaK Dependence of the Mycobacterial Stress-Responsive Regulator HspR Is Mediated through Its Hydrophobic C-Terminal Tail

Bandyopadhyay¹,

Gupta²,

Roy³

et al. 2012

Journal of Bacteriology

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HspR is a repressor known to control expression of heat shock operons in a number of Eubacteria. In mycobacteria and in several other actinobacteria, this protein is synthesized from the dnaKJE-hspR operon. Previous investigations revealed that HspR binds to the operon promoter, thereby controlling its expression in an autoregulatory manner. DnaK, which is a product of the same operon, further aids this autoregulatory process by stimulating the operator binding activity of HspR. The molecular mechanism by which DnaK assists HspR in executing its function is not clearly understood. In this study, it has been shown that DnaK can augment DNA binding activity of HspR by two mechanisms: (i) DnaK can restore the activity of completely denatured HspR by forming a complex with it, and (ii) DnaK can prevent thermal instability of HspR renatured by other means. Unlike the first mechanism, the latter function does not involve complex formation. The C-terminal hydrophobic tail of HspR was found to play a significant role in determining its thermal stability and DnaK dependence properties. A deletion mutant in which this region is removed does not respond to thermal stress and functions independent of DnaK. The hydrophobic C-terminal tails of HspRs of Mycobacterium tuberculosis and related Actinomycetales therefore may have evolved to make these HspRs more sensitive to thermal stress and, at the same time, subject to regulation by DnaK.

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“…It is a class 3 (acr3) sHSP [21] and homologues of sHSPs of the same class are found in Mycobacterium smegmatis, Mycobacterium marinum and Mycobacterium avium [22]. In 1988, Nerland et al [23] characterized this sHSP.…”

Section: Introductionmentioning

confidence: 99%

A S52P mutation in the ‘α‐crystallin domain’ of Mycobacterium leprae HSP18 reduces its oligomeric size and chaperone function

et al. 2013

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Mycobacterium leprae HSP18 is a small heat shock protein (sHSP). It is a major immunodominant antigen of M. leprae pathogen. Previously, we have reported the existence of two M. leprae HSP18 variants in various leprotic patients. One of the variants has serine at position 52, whereas the other one has proline at the same position. We have also reported that HSP18 having proline at position 52 ( HSP18P 52 ) is a nonameric protein and exhibits chaperone function. However, the structural and functional characterization of wild-type HSP18 having serine at position 52 ( HSP18S 52 ) is yet to be explored. Furthermore, the implications of the S52P mutation on the structure and chaperone function of HSP18 are not well understood. Therefore, we cloned and purified these two HSP18 variants. We found that HSP18S 52 is also a molecular chaperone and an oligomeric protein. Intrinsic tryptophan fluorescence and far-UV CD measurements revealed that the S52P mutation altered the tertiary and secondary structure of HSP18. This point mutation also reduced the oligomeric assembly and decreased the surface hydrophobicity of HSP18, as revealed by HPLC and 4,4′-dianilino-1,1′-binaphthyl-5,5′-disulfonic acid binding studies, respectively. Mutant protein was less stable against thermal and chemical denaturation and was more susceptible towards tryptic cleavage than wild-type HSP18. HSP18P 52 had lower chaperone function and was less effective in protecting thermal killing of Escherichia coli than HSP18S 52. Taken together, our data suggest that serine 52 is important for the larger oligomerization and chaperone function of HSP18. Because both variants differ in stability and function, they may have different roles in the survival of M. leprae in infected hosts. Abbreviations ACD, a-crystallin domain; bis-ANS, 4,4′-dianilino-1,1′-binaphthyl-5,5′-disulfonic acid, dipotassium salt; CFU, colony-forming unit; FRET, F€ orster resonance energy transfer; Gu-HCl, guanidine hydrochloride; IPTG, isopropyl thio-b-D-galactoside; MDH, malate dehydrogenase; sHSP, small heat shock protein. Structured digital abstract

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The stress‐responsive chaperone α‐crystallin 2 is required for pathogenesis of Mycobacterium tuberculosis

Cited by 76 publications

References 40 publications

Loss-of-Function Mutations in HspR Rescue the Growth Defect of a Mycobacterium tuberculosis Proteasome Accessory Factor E ( pafE ) Mutant

Loss-of-Function Mutations in HspR Rescue the Growth Defect of a Mycobacterium tuberculosis Proteasome Accessory Factor E ( pafE ) Mutant

DnaK Dependence of the Mycobacterial Stress-Responsive Regulator HspR Is Mediated through Its Hydrophobic C-Terminal Tail

A S52P mutation in the ‘α‐crystallin domain’ of Mycobacterium leprae HSP18 reduces its oligomeric size and chaperone function

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