Mycobacteria Encode Active and Inactive Classes of TesB Fatty-Acyl CoA Thioesterases Revealed through Structural and Functional Analysis.
Mycobacteria contain a large number of highly divergent species and exhibit unusual lipid metabolism profiles, believed to play important roles in immune invasion. Thioesterases modulate lipid metabolism through the hydrolysis of activated fatty-acyl CoAs; multiple copies are present in mycobacteria, yet many remain uncharacterized. Here, we undertake a comprehensive structural and functional analysis of a TesB thioesterase from Mycobacterium avium (MaTesB). Structural superposition with other TesB thioesterases reveals that the Asp active site residue, highly conserved across a wide range of TesB thioesterases, is mutated to Ala. Consistent with these structural data, the wild-type enzyme failed to hydrolyze an extensive range of acyl-CoA substrates. Mutation of this residue to an active Asp residue restored activity against a range of medium-chain length fatty-acyl CoA substrates. Interestingly, this Ala mutation is highly conserved across a wide range of Mycobacterium species but not found in any other bacteria or organism. Our structural homology analysis revealed that at least one other TesB acyl-CoA thioesterase also contains an Ala residue at the active site, while two other Mycobacterium TesB thioesterases harbor an Asp residue at the active site. The inactive TesBs display a common quaternary structure that is distinct from that of the active TesB thioesterases. Investigation of the effect of expression of either the catalytically active or inactive MaTesB in Mycobacterium smegmatis exposed, to the best of our knowledge, the first genotype-phenotype association implicating a mycobacterial tesB gene. This is the first report that mycobacteria encode active and inactive forms of thioesterases, the latter of which appear to be unique to mycobacteria.
School of Biomedical Sciences, Charles Sturt University , Wagga Wagga, New South Wales 2678, Australia.
Crystall M D
CM
Swarbrick
Department of Biology, Brooklyn College, City University of New York , 2900 Bedford Avenue, Brooklyn, New York 11210, United States.|Biology Program, Graduate Center, City University of New York , 365 Fifth Avenue, New York, New York 10016, United States.
Glennon V
GV
Bythrow
Australian Synchrotron , 800 Blackburn Road, Clayton, Victoria 3168, Australia.
David
D
Aragao
Department of Biology, Brooklyn College, City University of New York , 2900 Bedford Avenue, Brooklyn, New York 11210, United States.|Biology Program, Graduate Center, City University of New York , 365 Fifth Avenue, New York, New York 10016, United States.
Gabrielle A
GA
Germain
Department of Biology, Brooklyn College, City University of New York , 2900 Bedford Avenue, Brooklyn, New York 11210, United States.|Biology and Biochemistry Programs, Graduate Center, City University of New York , 365 Fifth Avenue, New York, New York 10016, United States.
Luis E N
LE
Quadri
School of Biomedical Sciences, Charles Sturt University , Wagga Wagga, New South Wales 2678, Australia.
Jade K
0000-0003-3267-9997
JK
Forwood
D000214:Acyl Coenzyme A / Q000737:chemistry* / Q000378:metabolism; D000409:Alanine / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001224:Aspartic Acid / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D015870:Gene Expression; D056726:Genetic Association Studies; D006868:Hydrolysis; D007527:Isoenzymes / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D009162:Mycobacterium avium / Q000201:enzymology* / Q000235:genetics; D020102:Mycobacterium smegmatis / Q000201:enzymology* / Q000235:genetics; D010170:Palmitoyl-CoA Hydrolase / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism; D000072417:Protein Domains; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
D000214:Acyl Coenzyme A; D001426:Bacterial Proteins; D007527:Isoenzymes; D011994:Recombinant Proteins; D001224:Aspartic Acid; D010170:Palmitoyl-CoA Hydrolase; D000409:Alanine