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Alternate quinone coupling in a new class of succinate dehydrogenase may potentiate mycobacterial respiratory control
Author(s) -
Hards Kiel,
Rodriguez Salome Molano,
Cairns Charlotte,
Cook Gregory M.
Publication year - 2019
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.13330
Subject(s) - mycobacterium smegmatis , succinate dehydrogenase , cofactor , mycobacterium , biochemistry , heme , quinone , respiratory chain , chemistry , dehydrogenase , bacteria , stereochemistry , enzyme , mycobacterium tuberculosis , biology , tuberculosis , medicine , pathology , genetics
There is a paucity of information on the unique components that pathogens use to form respiratory chains. It is not known why mycobacteria encode multiple succinate dehydrogenases ( SDH s) to perform menaquinone‐linked succinate oxidation, a thermodynamically unfavorable reaction (Δ G ° = +21 kJ·mol −1 ). In other bacteria, specific di‐heme SDH s overcome this using the proton motive force. It is unknown if this holds true in mycobacteria. Here, succinate dehydrogenase 1 (Sdh1) from Mycobacterium smegmatis was purified and found to not contain heme cofactors. Proteoliposomes, containing Sdh1, are active with coenzyme Q 2 ( K m ~ 12 μ m ), are competitively inhibited by menaquinone ( K i ~ 25 μ m ) and do not generate or consume electrochemical gradients. Sdh1 may use higher potential quinones in vivo and forms a novel SDH class, which we term ‘Type F’.