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.
Mycobacterium Biology Laboratory, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609. thomas.dick@group.novartis.com
Indrajit
I
Sinha
Calvin
C
Boon
Thomas
T
Dick
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