Conformational Control of UDP-Galactopyranose Mutase Inhibition

Journal Article · Tue Jun 13 00:00:00 EDT 2017 · Biochemistry

DOI:https://doi.org/10.1021/acs.biochem.7b00189· OSTI ID:1374629

Wangkanont, Kittikhun ^[1]; Winton, Valerie J. ^[2]; Forest, Katrina T. ^[2]; Kiessling, Laura L. ^[2]

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1. Univ. of Wisconsin, Madison, WI (United States); Chulalongkorn Univ., Bangkok (Thailand)
2. Univ. of Wisconsin, Madison, WI (United States)

UDP-galactopyranose mutase (Glf or UGM) catalyzes the formation of uridine 5'-diphosphate-α-d-galactofuranose (UDP-Galf) from UDP-galactopyranose (UDP-Galp). The enzyme is required for the production of Galf-containing glycans. UGM is absent in mammals, but members of the Corynebacterineae suborder require UGM for cell envelope biosynthesis. The need for UGM in some pathogens has prompted the search for inhibitors that could serve as antibiotic leads. Optimizing inhibitor potency, however, has been challenging. The UGM from Klebsiella pneumoniae (KpUGM), which is not required for viability, is more effectively impeded by small-molecule inhibitors than are essential UGMs from species such as Mycobacterium tuberculosis or Corynebacterium diphtheriae. Why KpUGM is more susceptible to inhibition than other orthologs is not clear. One potential source of difference is UGM ortholog conformation. We previously determined a structure of CdUGM bound to a triazolothiadiazine inhibitor in the open form, but it was unclear whether the small-molecule inhibitor bound this form or to the closed form. By varying the terminal tag (CdUGM-His6 and GSG-CdUGM), we crystallized CdUGM to capture the enzyme in different conformations. Furthermore, these structures reveal a pocket in the active site that can be exploited to augment inhibitor affinity. Moreover, they suggest the inhibitor binds the open form of most prokaryotic UGMs but can bind the closed form of KpUGM. This model and the structures suggest strategies for optimizing inhibitor potency by exploiting UGM conformational flexibility.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: Michigan Economic Development Corp.; Michigan Technology Tri-Corridor; National Inst. of Allergy and Infectious Disease; National Institute of General Medical Sciences (NIGMS); National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division
• Grant/Contract Number: AC02-06CH11357; AC02-76SF00515
• OSTI ID: 1374629
• Journal Information: Biochemistry, Journal Name: Biochemistry Journal Issue: 30 Vol. 56; ISSN 0006-2960
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
chemical structure
conformation
crystal structure
crystals
inhibitors