7DQ5 image
Entry Detail
PDB ID:
7DQ5
Keywords:
Title:
Crystal structure of HitB in complex with (S)-beta-phenylalanine sulfamoyladenosine
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2020-12-22
Release Date:
2021-03-03
Method Details:
Experimental Method:
Resolution:
2.45 Å
R-Value Free:
0.26
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Putative ATP-dependent b-aminoacyl-ACP synthetase
Chain IDs:A, B
Chain Length:549
Number of Molecules:2
Biological Source:Embleya scabrispora
Primary Citation
Mutational Biosynthesis of Hitachimycin Analogs Controlled by the beta-Amino Acid-Selective Adenylation Enzyme HitB.
Acs Chem.Biol. 16 539 547 (2021)
PMID: 33625847 DOI: 10.1021/acschembio.1c00003

Abstact

Hitachimycin is a macrolactam antibiotic with an (S)-β-phenylalanine (β-Phe) at the starter position of its polyketide skeleton. (S)-β-Phe is formed from l-α-phenylalanine by the phenylananine-2,3-aminomutase HitA in the hitachimycin biosynthetic pathway. In this study, we produced new hitachimycin analogs via mutasynthesis by feeding various (S)-β-Phe analogs to a ΔhitA strain. We obtained six hitachimycin analogs with F at the ortho, meta, or para position and Cl, Br, or a CH3 group at the meta position of the phenyl moiety, as well as two hitachimycin analogs with thienyl substitutions. Furthermore, we carried out a biochemical and structural analysis of HitB, a β-amino acid-selective adenylation enzyme that introduces (S)-β-Phe into the hitachimycin biosynthetic pathway. The KM values of the incorporated (S)-β-Phe analogs and natural (S)-β-Phe were similar. However, the KM values of unincorporated (S)-β-Phe analogs with Br and a CH3 group at the ortho or para position of the phenyl moiety were high, indicating that HitB functions as a gatekeeper to select macrolactam starter units during mutasynthesis. The crystal structure of HitB in complex with (S)-β-3-Br-phenylalanine sulfamoyladenosine (β-m-Br-Phe-SA) revealed that the bulky meta-Br group is accommodated by the conformational flexibility around Phe328, whose side chain is close to the meta position. The aromatic group of β-m-Br-Phe-SA is surrounded by hydrophobic and aromatic residues, which appears to confer the conformational flexibility that enables HitB to accommodate the meta-substituted (S)-β-Phe. The new hitachimycin analogs exhibited different levels of biological activity in HeLa cells and multidrug-sensitive budding yeast, suggesting that they may target different molecules.

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