TY - JOUR
T1 - The Crystal Structure of a Plant 3-Ketoacyl-CoA Thiolase Reveals the Potential for Redox Control of Peroxisomal Fatty Acid β-Oxidation
AU - Sundaramoorthy, Ramasubramanian
AU - Micossi, Elena
AU - Alphey, Magnus S.
AU - Germain, Véronique
AU - Bryce, James H.
AU - Smith, Steve M.
AU - Leonard, Gordon A.
AU - Hunter, William N.
PY - 2006/6/2
Y1 - 2006/6/2
N2 - Crystal structures of peroxisomal Arabidopsis thaliana 3-ketoacyl-CoA thiolase (AtKAT), an enzyme of fatty acid ß-oxidation, are reported. The subunit, a typical thiolase, is a combination of two similar a/ß domains capped with a loop domain. The comparison of AtKAT with the Saccharomyces cerevisiae homologue (ScKAT) structure reveals a different placement of subunits within the functional dimers and that a polypeptide segment forming an extended loop around the open catalytic pocket of ScKAT converts to a-helix in AtKAT, and occludes the active site. A disulfide is formed between Cys192, on this helix, and Cys138, a catalytic residue. Access to Cys138 is determined by the structure of this polypeptide segment. AtKAT represents an oxidized, previously unknown inactive form, whilst ScKAT is the reduced and active enzyme. A high level of sequence conservation is observed, including Cys192, in eukaryotic peroxisomal, but not mitochondrial or prokaryotic KAT sequences, for this labile loop/helix segment. This indicates that KAT activity in peroxisomes is influenced by a disulfide/dithiol change linking fatty acid ß-oxidation with redox regulation. © 2006 Elsevier Ltd. All rights reserved.
AB - Crystal structures of peroxisomal Arabidopsis thaliana 3-ketoacyl-CoA thiolase (AtKAT), an enzyme of fatty acid ß-oxidation, are reported. The subunit, a typical thiolase, is a combination of two similar a/ß domains capped with a loop domain. The comparison of AtKAT with the Saccharomyces cerevisiae homologue (ScKAT) structure reveals a different placement of subunits within the functional dimers and that a polypeptide segment forming an extended loop around the open catalytic pocket of ScKAT converts to a-helix in AtKAT, and occludes the active site. A disulfide is formed between Cys192, on this helix, and Cys138, a catalytic residue. Access to Cys138 is determined by the structure of this polypeptide segment. AtKAT represents an oxidized, previously unknown inactive form, whilst ScKAT is the reduced and active enzyme. A high level of sequence conservation is observed, including Cys192, in eukaryotic peroxisomal, but not mitochondrial or prokaryotic KAT sequences, for this labile loop/helix segment. This indicates that KAT activity in peroxisomes is influenced by a disulfide/dithiol change linking fatty acid ß-oxidation with redox regulation. © 2006 Elsevier Ltd. All rights reserved.
KW - β-oxidation
KW - 3-ketoacyl-CoA thiolase
KW - Arabidopsis thaliana
KW - redox regulation
KW - Saccharomyces cerevisiae
UR - http://www.scopus.com/inward/record.url?scp=33646202811&partnerID=8YFLogxK
U2 - 10.1016/j.jmb.2006.03.032
DO - 10.1016/j.jmb.2006.03.032
M3 - Article
C2 - 16630629
SN - 0022-2836
VL - 359
SP - 347
EP - 357
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 2
ER -