7N63

X-ray structure of HCAN_0200, an aminotransferase from Helicobacter canadensis in complex with its external aldimine

Summary for 7N63

• Entry DOI: 10.2210/pdb7n63/pdb
• Descriptor: Putative aminotransferase, (2R,3R,4S,5S,6R)-3,5-dihydroxy-4-{[(1E)-{3-hydroxy-2-methyl-5-[(phosphonooxy)methyl]pyridin-4-yl}methylidene]amino}-6-methyltetrahydro-2H-pyran-2-yl [(2R,3S,5R)-3-hydroxy-5-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)tetrahydrofuran-2-yl]methyl dihydrogen diphosphate, MAGNESIUM ION, ... (6 entities in total)
• Functional Keywords: aminotransferase, pyridoxyl phosphate, external aldimine, transferase
• Biological source: Helicobacter canadensis MIT 98-5491
• Total number of polymer chains: 1
• Total formula weight: 43648.42

Authors

Griffiths, W.A.,Heisdorf, C.J.,Thoden, J.B.,Holden, H.M. (deposition date: 2021-06-07, release date: 2021-06-23, Last modification date: 2023-10-18)

Primary citation

Heisdorf, C.J.,Griffiths, W.A.,Thoden, J.B.,Holden, H.M.
Investigation of the enzymes required for the biosynthesis of an unusual formylated sugar in the emerging human pathogen Helicobacter canadensis.
Protein Sci., 30:2144-2160, 2021

PubMed Abstract: It is now well established that the Gram-negative bacterium, Helicobacter pylori, causes gastritis in humans. In recent years, it has become apparent that the so-called non-pylori Helicobacters, normally infecting pigs, cats, and dogs, may also be involved in human pathology via zoonotic transmission. Indeed, more than 30 species of non-pylori Helicobacters have been identified thus far. One such organism is Helicobacter canadensis, an emerging pathogen whose genome sequence was published in 2009. Given our long-standing interest in the biosynthesis of N-formylated sugars found in the O-antigens of some Gram-negative bacteria, we were curious as to whether H. canadensis produces such unusual carbohydrates. Here, we demonstrate using both biochemical and structural techniques that the proteins encoded by the HCAN_0198, HCAN_0204, and HCAN_0200 genes in H. canadensis, correspond to a 3,4-ketoisomerase, a pyridoxal 5'-phosphate aminotransferase, and an N-formyltransferase, respectively. For this investigation, five high-resolution X-ray structures were determined and the kinetic parameters for the isomerase and the N-formyltransferase were measured. Based on these data, we suggest that the unusual sugar, 3-formamido-3,6-dideoxy-d-glucose, will most likely be found in the O-antigen of H. canadensis. Whether N-formylated sugars found in the O-antigen contribute to virulence is presently unclear, but it is intriguing that they have been observed in such pathogens as Francisella tularensis, Mycobacterium tuberculosis, and Brucella melitensis.

PubMed: 34379357
DOI: 10.1002/pro.4169

Experimental method

X-RAY DIFFRACTION (1.4 Å)