A conserved motif flags acyl carrier proteins for β-branching in polyketide synthesis.
Type I polyketide synthases often use programmed β-branching, via enzymes of a 'hydroxymethylglutaryl-CoA synthase (HCS) cassette', to incorporate various side chains at the second carbon from the terminal carboxylic acid of growing polyketide backbones. We identified a strong sequence motif in acyl carrier proteins (ACPs) where β-branching is known to occur. Substituting ACPs confirmed a correlation of ACP type with β-branching specificity. Although these ACPs often occur in tandem, NMR analysis of tandem β-branching ACPs indicated no ACP-ACP synergistic effects and revealed that the conserved sequence motif forms an internal core rather than an exposed patch. Modeling and mutagenesis identified ACP helix III as a probable anchor point of the ACP-HCS complex whose position is determined by the core. Mutating the core affects ACP functionality, whereas ACP-HCS interface substitutions modulate system specificity. Our method for predicting β-carbon branching expands the potential for engineering new polyketides and lays a basis for determining specificity rules.
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Anthony S
AS
Haines
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
Xu
X
Dong
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
Zhongshu
Z
Song
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Rohit
R
Farmer
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
Christopher
C
Williams
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Joanne
J
Hothersall
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
Eliza
E
Płoskoń
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
Pakorn
P
Wattana-Amorn
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Elton R
ER
Stephens
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Erika
E
Yamada
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Rachel
R
Gurney
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Yuiko
Y
Takebayashi
Division of Gene Technology, KU Leuven, Kasteelpark Arenberg 21 - box 2462, 3001 Heverlee, Belgium.
Joleen
J
Masschelein
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
Russell J
RJ
Cox
Division of Gene Technology, KU Leuven, Kasteelpark Arenberg 21 - box 2462, 3001 Heverlee, Belgium.
Rob
R
Lavigne
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
Christine L
CL
Willis
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
Thomas J
TJ
Simpson
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
John
J
Crosby
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Peter J
PJ
Winn
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
Christopher M
CM
Thomas
School of Chemistry, Cantock's Close, Clifton, Bristol, BS8 1TS, UK.
Matthew P
MP
Crump
D000213:Acyl Carrier Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D017124:Conserved Sequence; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000378:metabolism*; D008958:Models, Molecular; D008968:Molecular Conformation; D061065:Polyketides / Q000737:chemistry / Q000378:metabolism*
D000213:Acyl Carrier Protein; D061065:Polyketides; D006904:Hydroxymethylglutaryl-CoA Synthase