title: Functional complementation of the essential gene fabG1 of Mycobacterium tuberculosis by Mycobacterium smegmatis fabG but not Escherichia coli fabG.
abstract: Mycolic acids are a key component of the mycobacterial cell wall, providing structure and forming a major permeability barrier. In Mycobacterium tuberculosis mycolic acids are synthesized by type I and type II fatty acid synthases. One of the enzymes of the type II system is encoded by fabG1. We demonstrate here that this gene can be deleted from the M. tuberculosis chromosome only when another functional copy is provided elsewhere, showing that under normal culture conditions fabG1 is essential. FabG1 activity can be replaced by the corresponding enzyme from the closely related species Mycobacterium smegmatis but not by the enzyme from Escherichia coli. M. tuberculosis carrying FabG from M. smegmatis showed no phenotypic changes, and both the mycolic acids and cell wall permeability were unchanged. Thus, M. tuberculosis and M. smegmatis enzymes are interchangeable and do not control the lengths and types of mycolic acids synthesized.
authors.affiliation: Centre for Infectious Disease, Institute of Cell and Molecular Science, Barts and the London, London E1 2AT, United Kingdom. t.parish@qmul.ac.uk
authors.forename: Tanya
authors.initials: T
authors.lastname: Parish
authors.forename: Gretta
authors.initials: G
authors.lastname: Roberts
authors.forename: Francoise
authors.initials: F
authors.lastname: Laval
authors.forename: Merrill
authors.initials: M
authors.lastname: Schaeffer
authors.forename: Mamadou
authors.initials: M
authors.lastname: Daffé
authors.forename: Ken
authors.initials: K
authors.lastname: Duncan
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics*; D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000201:enzymology* / Q000235:genetics; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics; D009171:Mycolic Acids / Q000378:metabolism*; D010641:Phenotype; D013045:Species Specificity
chemical_list: D009171:Mycolic Acids; D000429:Alcohol Oxidoreductases; C023744:acetoacetyl-CoA reductase