PMID- 20364820
OWN - NLM
STAT- MEDLINE
DCOM- 20100524
LR  - 20100427
IS  - 1520-4995 (Electronic)
IS  - 0006-2960 (Linking)
VI  - 49
IP  - 17
DP  - 2010 May 4
TI  - Comparison of two metal-dependent pyruvate aldolases related by convergent 
      evolution: substrate specificity, kinetic mechanism, and substrate channeling.
PG  - 3774-82
LID - 10.1021/bi100251u [doi]
AB  - HpaI and BphI are two pyruvate class II aldolases found in aromatic meta-cleavage 
      degradation pathways that catalyze similar reactions but are not related in 
      sequence. Steady-state kinetic analysis of the aldol addition reactions and 
      product inhibition assays showed that HpaI exhibits a rapid equilibrium random 
      order mechanism while BphI exhibits a compulsory order mechanism, with pyruvate 
      binding first. Both aldolases are able to utilize aldehyde acceptors two to five 
      carbons in length; however, HpaI showed broader specificity and had a preference 
      for aldehydes containing longer linear alkyl chains or C2-OH substitutions. Both 
      enzymes were able to bind 2-keto acids larger than pyruvate, but only HpaI was 
      able to utilize both pyruvate and 2-ketobutanoate as carbonyl donors in the aldol 
      addition reaction. HpaI lacks stereospecific control producing racemic mixtures 
      of 4-hydroxy-2-oxopentanoate (HOPA) from pyruvate and acetaldehyde while BphI 
      synthesizes only (4S)-HOPA. BphI is also able to utilize acetaldehyde produced by 
      the reduction of acetyl-CoA catalyzed by the associated aldehyde dehydrogenase, 
      BphJ. This aldehyde was directly channeled from the dehydrogenase to the aldolase 
      active sites, with an efficiency of 84%. Furthermore, the BphJ reductive 
      deacylation reaction increased 4-fold when BphI was catalyzing the aldol addition 
      reaction. Therefore, the BphI-BphJ enzyme complex exhibits unique 
      bidirectionality in substrate channeling and allosteric activation.
FAU - Wang, Weijun
AU  - Wang W
AD  - Department of Molecular and Cellular Biology, University of Guelph, Guelph, 
      Ontario, Canada N1G 2W1.
FAU - Baker, Perrin
AU  - Baker P
FAU - Seah, Stephen Y K
AU  - Seah SY
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Aldehydes)
RN  - 0 (Escherichia coli Proteins)
RN  - 0 (Pyruvates)
RN  - EC 1.2.1.3 (Aldehyde Dehydrogenase)
RN  - EC 4.1.2.- (Aldehyde-Lyases)
RN  - EC 4.1.2.- (HpaI protein, E coli)
SB  - IM
MH  - Aldehyde Dehydrogenase/*metabolism
MH  - Aldehyde-Lyases/*metabolism
MH  - Aldehydes/*metabolism
MH  - Binding Sites
MH  - Catalysis
MH  - Catalytic Domain
MH  - Escherichia coli Proteins/*metabolism
MH  - *Evolution, Molecular
MH  - Kinetics
MH  - Protein Conformation
MH  - Pyruvates/*metabolism
MH  - Stereoisomerism
MH  - Substrate Specificity
EDAT- 2010/04/07 06:00
MHDA- 2010/05/25 06:00
CRDT- 2010/04/07 06:00
PHST- 2010/04/07 06:00 [entrez]
PHST- 2010/04/07 06:00 [pubmed]
PHST- 2010/05/25 06:00 [medline]
AID - 10.1021/bi100251u [doi]
PST - ppublish
SO  - Biochemistry. 2010 May 4;49(17):3774-82. doi: 10.1021/bi100251u.