Loss of a mycobacterial gene encoding a reductase leads to an altered cell wall containing β-oxo- mycolic acid analogs and accumulation of ketones

Apoorva Bhatt, Alistair Brown, Albel Singh, David E. Minnikin, Gurdyal Besra

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

Mycolic acids are essential components of the mycobacterial cell wall. In this study, we show that a gene encoding a reductase involved in the final step of mycolic acid biosynthesis can be deleted in Mycobacterium smegmatis without affecting cell viability. Deletion of MSMEG4722 (ortholog of Mycobacterium tuberculosis Rv2509) altered culture characteristics and antibiotic sensitivity. The ΔMSMEG4722 strain synthesized α-alkyl, β-oxo intermediates of mycolic acids, which were found esterified to cell wall arabinogalactan. While the precursors could not be isolated directly due to their inherent instability during base treatment, their presence was established by prior reduction of the β-oxo group by sodium borohydride. Interestingly, the mutant also accumulated unsaturated ketones, similar to tuberculenone from M. tuberculosis, which were shunt products derived from spontaneous decarboxylation of α-alkyl, β-oxo fatty acid precursors of mycolic acids.
Original languageEnglish
Pages (from-to)930-939
JournalChemistry & Biology
Volume15
Issue number9
DOIs
Publication statusPublished - 2008

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