Steric Control of the Rate-Limiting Step of UDP-Galactopyranose Mutase

Biochemistry
Gustavo Pierdominici-SottilePablo Sobrado

Abstract

Galactose is an abundant monosaccharide found exclusively in mammals as galactopyranose (Gal p), the six-membered ring form of this sugar. In contrast, galactose appears in many pathogenic microorganisms as the five-membered ring form, galactofuranose (Gal f). Gal f biosynthesis begins with the conversion of UDP-Gal p to UDP-Gal f catalyzed by the flavoenzyme UDP-galactopyranose mutase (UGM). Because UGM is essential for the survival and proliferation of several pathogens, there is interest in understanding the catalytic mechanism to aid inhibitor development. Herein, we have used kinetic measurements and molecular dynamics simulations to explore the features of UGM that control the rate-limiting step (RLS). We show that UGM from the pathogenic fungus Aspergillus fumigatus also catalyzes the isomerization of UDP-arabinopyranose (UDP-Ara p), which differs from UDP-Gal p by lacking a -CH2-OH substituent at the C5 position of the hexose ring. Unexpectedly, the RLS changed from a chemical step for the natural substrate to product release with UDP-Ara p. This result implicated residues that contact the -CH2-OH of UDP-Gal p in controlling the mechanistic path. The mutation of one of these residues, Trp315, to Ala changed the RLS of t...Continue Reading

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Citations

Nov 17, 2020·Frontiers in Molecular Biosciences·Brett A Beaupre, Graham R Moran
Jan 5, 2019·Journal of Chemical Information and Modeling·Rodrigo Cossio-PérezJuliana Palma

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Aspergillosis (ASM)

Aspergillosis is the name given to a wide variety of diseases caused by infection by fungi of the genus Aspergillus. Aspergillosis occurs in chronic or acute forms which are clinically very distinct. Most cases of acute aspergillosis occur in patients with severely compromised immune systems. Chronic colonization or infection can cause complications in people with underlying respiratory illnesses. Discover the latest research on aspergillosis here.

Aspergillosis

Aspergillosis is the name given to a wide variety of diseases caused by infection by fungi of the genus Aspergillus. Aspergillosis occurs in chronic or acute forms which are clinically very distinct. Most cases of acute aspergillosis occur in patients with severely compromised immune systems. Chronic colonization or infection can cause complications in people with underlying respiratory illnesses. Discover the latest research on aspergillosis here.