title: Expression and localization of the Mycobacterium tuberculosis protein tyrosine phosphatase PtpA.
abstract: The Mycobacterium tuberculosis open reading frame Rv2234 encodes a low molecular weight tyrosine phosphatase named PtpA. Kinetic analyses of PtpA activity reveal that it is capable of dephosphorylation of p-nitrophenyl phosphate, as well as a variety of phosphotyrosine-containing substrates. In contrast, PtpA showed no detectable activity towards substrates containing phosphoserine or -threonine residues. Transcriptional analysis reveals that the M. tuberculosis ptpA promoter is expressed in the slow-growing Mycobacterium species M. bovis BCG, but not in the fast-growing species M. smegmatis. Furthermore, ptpA expression is upregulated upon entry of BCG cultures into stationary phase and increases upon infection of human monocytes. We also show that, despite the lack of a general export pathway signal sequence, the M. tuberculosis PtpA protein can be released from both M. tuberculosis and M. smegmatis during growth.
authors.affiliation: Department of Medicine, University of British Columbia, Vancouver, Canada.
authors.forename: Siobhán C
authors.initials: SC
authors.lastname: Cowley
authors.forename: Ryan
authors.initials: R
authors.lastname: Babakaiff
authors.forename: Yossef
authors.initials: Y
authors.lastname: Av-Gay
mesh_terms: D002460:Cell Line; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008264:Macrophages / Q000382:microbiology; D009163:Mycobacterium bovis / Q000201:enzymology / Q000254:growth & development; D020102:Mycobacterium smegmatis / Q000201:enzymology / Q000254:growth & development; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000254:growth & development; D019000:Phosphotyrosine / Q000737:chemistry / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity; D014158:Transcription, Genetic
chemical_list: D019000:Phosphotyrosine; D017027:Protein Tyrosine Phosphatases