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Upregulation of galactose metabolic pathway by N-Acetylglucosamine induced endogenous synthesis of galactose in Candida albicans

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Title Upregulation of galactose metabolic pathway by N-Acetylglucosamine induced endogenous synthesis of galactose in Candida albicans
 
Creator Kamthan, Mohan
Kamthan, Ayushi
Ruhela, Deepa
Maiti, Protiti
Bhavesh, Neel Sarovar
Datta, Asis
 
Subject Candida
N-acetylglucosamine
GAL1
GAL10
Endogenous galactose
 
Description Accepted date: 9 February 2013
N-Acetylglucosamine (GlcNAc) is an important signaling molecule that plays multiple roles in Candida albicans. Induction of galactose metabolic pathway by GlcNAc is an intriguing aspect of C. albicans biology. In order to investigate the role of galactose metabolic genes (GAL genes) in presence of GlcNAc, we created knockouts of galactokinase (GAL1) and UDP galactose epimerase (GAL10) genes. These mutants failed to grow on galactose and also showed lower growth rate in presence of GlcNAc. Interestingly, expression of GAL genes in presence of GlcNAc was higher in gal1Δ strain relative to that of wild type strain. Moreover, no GlcNAc induced upregulation of GAL genes was observed in the gal10Δ strain suggesting that UDP galactose epimerase is essential for GlcNAc induced activation of GAL genes. GlcNAc induced expression of GAL genes was also investigated in GlcNAc metabolic pathway triple mutant N216 (hxk1Δ nag1Δ dac1Δ). Interestingly, in this mutant the GAL genes are neither induced nor repressed and remain derepressed as found on a neutral carbon source such as glycerol, suggesting that catabolism of GlcNAc play an important role in the expression of GAL genes. GC/MS analysis of derivatized metabolites revealed a significant accumulation of galactose in the gal1Δ strain while no galactose was detected in gal10Δ and N216 strain. Solution-state NMR spectroscopy using N-acetyl-¹³C₁-glucosamine confirmed the flow of ¹³C label from GlcNAc to galactose. Thus, internal galactose synthesized via UDP galactose pathway from GlcNAc metabolites acts as the inducer of GAL genes in presence of GlcNAc.
We wish to thank Mr. Ashok Kumar for providing the technical
assistance in qRT-PCR. This work is supported by the Department
of Biotechnology, Ministry of Science and Technology, Government
of India. We also thank Department of Biotechnology (DBT), Government of India for providing financial support for the 500 MHz
and 700 MHz NMR spectrometers at the ICGEB, New Delhi and
NII, New Delhi. MK thanks ICMR for the fellowship.
 
Date 2015-11-05T04:38:47Z
2015-11-05T04:38:47Z
2013
 
Type Article
 
Identifier Fungal Genet. Biol., 54: 15-24
1087-1845
http://172.16.0.77:8080/jspui/handle/123456789/318
http://www.sciencedirect.com/science/article/pii/S1087184513000303
10.1016/j.fgb.2013.02.006
 
Language en_US
 
Publisher Elsevier