Disease relevance of hspX

• Deletion of the Mycobacterium tuberculosis alpha-crystallin-like hspX gene causes increased bacterial growth in vivo [1].

High impact information on hspX

• A complete genomic microarray study demonstrated that SigC modulates the expression of several key virulence-associated genes including hspX, senX3 and mtrA, encoding the alpha-crystallin homologue, a two-component sensor kinase and a two-component response regulator respectively [2].
• Changes in the mRNA levels of two Mycobacterium tuberculosis genes (fbpB known as antigen 85B, and hspX known as Acr) were studied in infected human monocytes [3].
• The increased growth in macrophages was equal to that of a DeltadosR mutant, while introduction of a constitutively expressed hspX gene reduced the DeltadosR virulence to wild-type levels [1].
• The use of M. smegmatis as a tool for studying the mycobacterial stringent response was demonstrated by measuring the expression of two M. tuberculosis genes, hspX and eis, in M. smegmatis in the presence and absence of rel(Msm) [4].
• Primer extension analysis revealed that the transcription start site is located 33 nucleotides upstream of the hspX gene start codon [5].

Biological context of hspX

• This study gives new insights into the expression profiles of the different mce operons and the hspX and esat-6 genes in an in vitro model of dormant-like bacilli [6].

Analytical, diagnostic and therapeutic context of hspX

• Two transcripts of about 2.5 and 1.1 kb were demonstrated by Northern blot analysis and hybridized to the hspX gene probe [5].
• In a timed sampling study, using a slowly stirred oxygen depletion culture model, we have demonstrated that the hspX mRNA that codes for Acr protein as well as the protein itself is induced just as the bacilli enter the microaerophilic NRP stage 1 (NRP-1) [7].
• The RT-PCR results showed that mce-1a, mce-2a, hspX (encoding the alpha-crystallin antigen Acr) and esat-6 (encoding the early secretory antigenic target-6) were expressed throughout the cultivation period, whereas the expression of mce-3a and mce-4a was downregulated in the later stages of cultivation [6].
• We also demonstrated that hspX, which is dependent on dosR for expression, is induced when cultures are left standing for 30 min, while significant but minor induction was seen following a 10 min centrifugation [8].

References