Apparent growth phase-dependent phosphorylation of malonyl coenzyme A:acyl carrier protein transacylase (MCAT), a major fatty acid synthase II component in Mycobacterium bovis BCG.
Probing protein extracts from exponentially growing and stationary phase cultures of Mycobacterium bovis BCG with anti-phospho amino acid antibodies revealed a 31-kDa anti-phospho threonine antibody-reactive protein specific to growing culture. The corresponding protein was purified via two-dimensional gel electrophoresis and identified via mass spectrometry to be malonyl coenzyme A:acyl carrier protein transacylase (MCAT), a component of the fatty acid biosynthetic pathway. MCAT tagged with histidine reacted with anti-phospho threonine antibody and was positive in an in-gel chemical assay for phospho proteins. Analysis of the growth phase dependence of MCAT-His phosphorylation and protein levels showed that phosphorylated MCAT-His can be detected only in growing culture. In contrast, MCAT-His protein level was growth phase-independent. These results suggest that MCAT may be a substrate of a protein kinase and phosphatase, and that aspects of fatty acid synthesis in tubercle bacilli are regulated by protein phosphorylation.
Sinha
Indrajit
I
Mycobacterium Biology Laboratory, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609. thomas.dick@group.novartis.com
Boon
Calvin
C
Dick
Thomas
T
D051080:Acyl-Carrier Protein S-Malonyltransferase; D000217:Acyltransferases / Q000378:metabolism*; D064429:Fatty Acid Synthases / Q000737:chemistry; D009163:Mycobacterium bovis / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism; D010766:Phosphorylation
D000217:Acyltransferases; D051080:Acyl-Carrier Protein S-Malonyltransferase; D064429:Fatty Acid Synthases