Structure of the external aldimine form of PglE, an aminotransferase required for N,N'‐diacetylbacillosamine biosynthesis

Abstract

N,N'-diacetylbacillosamine is a novel sugar that plays a key role in bacterial glycosylation. Three enzymes are required for its biosynthesis in Campylobacter jejuni starting from UDPGlcNAc. The focus of this investigation, PglE, catalyzes the second step in the pathway. It is a PLP-dependent aminotransferase that converts UDP-2-acetamido-4-keto-2,4,6-trideoxy-D-glucose to UDP-2-acetamido-4-amino-2,4,6-trideoxy-D-glucose. For this investigation, the structure of PglE in complex with an external aldimine was determined to a nominal resolution of 2.0 Å . A comparison of its structure with those of other sugar aminotransferases reveals a remarkable difference in the manner by which PglE accommodates its nucleotide-linked sugar substrate.

Genomic Analysis of a New Serovar of Leptospira weilii Serogroup Manhao

“…Although most of the unique genes of rfb locus in strain L231 were hypothetical proteins, three genes encoding aminotransferase PglE were found (Supplementary Table S3 ). PglE belongs to the aspartate aminotransferase superfamily, and is involved in a novel sugar N,N′-diacetylbacillosamine biosynthesis, which contributes to bacterial membrane protein glycosylation ( Riegert et al, 2015 ). Furthermore, those differences may occur in different serovars from the same serogroup, providing further evidence that different Leptospira genospecies or strains may be classified as being in the same serogroup or serovar ( de la Pena-Moctezuma et al, 1999 ).…”

Structural investigation on WlaRG from Campylobacter jejuni: A sugar aminotransferase

“…The overall architecture of the WlaRG subunit places it into the well‐characterized aspartate aminotransferase family (Fold Type I) . As observed in other sugar aminotransferases, but certainly not all, Tyr 306 adopts the cis conformation with its side chain projecting in towards the active site region …”

“…17 As observed in other sugar aminotransferases, but certainly not all, Tyr 306 adopts the cis conformation with its side chain projecting in towards the active site region. 18 The next structure solved in this investigation was that of the Schiff base formed between the side chain of Lys 184 and PLP, referred to as the internal aldimine. The crystals of the complex diffracted to 1.5 Å resolution, and the final model was refined to an overall R-factor of 14.3%.…”

“…This enzyme is involved in the biosynthesis of UDP‐4‐amino‐4‐deoxy‐ l ‐arabinose, whose addition to lipid A results in bacterial resistance to cationic antimicrobial peptides . Other enzymes with known three‐dimensional structures that function on C‐4′ keto sugar substrates include PseC from Helicobacter pylori , DesI from Streptomyces venezuelae , perosamine synthase from Caulobacter crescentus , WecE from Escherichia coli, and PglE from C. jejuni …”

“…22 Other enzymes with known three-dimensional structures that function on C-4 0 keto sugar substrates include PseC from Helicobacter pylori, 23 DesI from Streptomyces venezuelae, 24 perosamine synthase from Caulobacter crescentus, 25 WecE from Escherichia coli, 26 and PglE from C. jejuni. 18 In contrast, only three models have been reported to date for those enzymes that function on C-3 0 keto moieties: DesV from Streptomyces venezuelae, QdtB from Thermoanaerobacterium thermosaccharolyticum E207-71, and WbpE from P. aeruginosa. 15,27,28 Each one of these enzymes serves a different biological role.…”