title: Essentiality and functional analysis of type I and type III pantothenate kinases of Mycobacterium tuberculosis.
abstract: Pantothenate kinase, an essential enzyme in bacteria and eukaryotes, is involved in catalysing the first step of conversion of pantothenate to coenzyme A (CoA). Three isoforms (type I, II and III) of this enzyme have been reported from various organisms, which can be differentiated from each other on the basis of their biochemical and structural characteristics. Though most bacteria carry only one of the isoforms of pantothenate kinases, some of them possess two isoforms. The physiological relevance of the presence of two types of isozymes in a single organism is not clear. Mycobacterium tuberculosis, an intracellular pathogen, possesses two isoforms of pantothenate kinases (CoaA and CoaX) belonging to type I and III. In order to determine which pantothenate kinase is essential in mycobacteria, we performed gene inactivation of coaA and coaX of M. tuberculosis individually. It was found that coaA could only be inactivated in the presence of an extra copy of the gene, while coaX could be inactivated in the wild-type cells, proving that CoaA is the essential pantothenate kinase in M. tuberculosis. Additionally, the coaA gene of M. tuberculosis was able to complement a temperature-sensitive coaA mutant of Escherichia coli at a non-permissive temperature while coaX could not. The coaX deletion mutant showed no growth defects in vitro, in macrophages or in mice. Taken together, our data suggest that CoaX, which is essential in Bacillus anthracis and thus had been suggested to be a drug target in this organism, might not be a valid target in M. tuberculosis. We have established that the type I isoform, CoaA, is the essential pantothenate kinase in M. tuberculosis and thus can be explored as a drug target.
authors.affiliation: AstraZeneca R & D, 'Avishkar' Bellary Road, Hebbal, Bangalore, India.
authors.forename: Disha
authors.initials: D
authors.lastname: Awasthy
authors.affiliation: AstraZeneca R & D, 'Avishkar' Bellary Road, Hebbal, Bangalore, India.
authors.forename: Anisha
authors.initials: A
authors.lastname: Ambady
authors.affiliation: AstraZeneca R & D, 'Avishkar' Bellary Road, Hebbal, Bangalore, India.
authors.forename: Jyothi
authors.initials: J
authors.lastname: Bhat
authors.affiliation: AstraZeneca R & D, 'Avishkar' Bellary Road, Hebbal, Bangalore, India.
authors.forename: Gulebahar
authors.initials: G
authors.lastname: Sheikh
authors.affiliation: AstraZeneca R & D, 'Avishkar' Bellary Road, Hebbal, Bangalore, India.
authors.forename: Sudha
authors.initials: S
authors.lastname: Ravishankar
authors.affiliation: AstraZeneca R & D, 'Avishkar' Bellary Road, Hebbal, Bangalore, India.
authors.forename: Venkita
authors.initials: V
authors.lastname: Subbulakshmi
authors.affiliation: AstraZeneca R & D, 'Avishkar' Bellary Road, Hebbal, Bangalore, India.
authors.forename: Kakoli
authors.initials: K
authors.lastname: Mukherjee
authors.affiliation: AstraZeneca R & D, 'Avishkar' Bellary Road, Hebbal, Bangalore, India.
authors.forename: Vasan
authors.initials: V
authors.lastname: Sambandamurthy
authors.affiliation: AstraZeneca R & D, 'Avishkar' Bellary Road, Hebbal, Bangalore, India.
authors.forename: Umender
authors.initials: U
authors.lastname: Sharma
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D014376:Tuberculosis / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D007527:Isoenzymes; D017853:Phosphotransferases (Alcohol Group Acceptor); C023088:pantothenate kinase