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AftD, a novel essential arabinofuranosyltransferase from mycobacteria

Henrieta Skovierová1, Gérald Larrouy-Maumus, Jian Zhang

  • 1Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.

Glycobiology
|August 6, 2009
PubMed

Insights

Mycobacterium tuberculosis cell wall synthesis involves arabinogalactan (AG) and lipoarabinomannan (LAM). Researchers identified AftD (Rv0236c) as a crucial arabinofuranosyltransferase (AraT) essential for AG and LAM biosynthesis.

Area of Science:

  • Microbiology
  • Biochemistry
  • Glycobiology

Background:

  • Arabinogalactan (AG) and lipoarabinomannan (LAM) are key mycobacterial cell wall polysaccharides.
  • Their shared arabinan chains, featuring alpha-1,5 and alpha-1,3 linkages, are potential targets for novel therapeutics.
  • The specific enzymes (arabinofuranosyltransferases or AraTs) responsible for their synthesis remain largely uncharacterized.

Purpose of the Study:

  • To identify and characterize the arabinofuranosyltransferases (AraTs) involved in synthesizing the arabinan domains of AG and LAM in Mycobacterium tuberculosis.
  • To investigate the function of the putative glycosyltransferase Rv0236c (AftD) in mycobacterial cell wall biosynthesis.

Main Methods:

  • Bioinformatic analysis to identify putative glycosyltransferases.
  • Recombinant expression of Rv0236c (AftD) in Mycobacterium smegmatis and Corynebacterium glutamicum.
  • In vitro enzymatic assays using cell-free extracts to assess glycosyltransferase activity.
  • Gene disruption and overexpression studies in M. smegmatis to evaluate AftD's role in cell viability and polysaccharide synthesis.

Main Results:

  • Rv0236c (AftD) was identified as a functional arabinofuranosyltransferase (AraT) with alpha-1,3-branching activity in vitro.
  • Disruption of aftD in M. smegmatis led to cell death, impaired cell division, reduced growth, and altered morphology.
  • Overexpression of aftD resulted in the accumulation of arabinosylated compounds resembling LAM backbones.

Conclusions:

  • AftD is an essential arabinofuranosyltransferase (AraT) critical for the biosynthesis of the arabinan domain in major mycobacterial cell envelope polysaccharides.
  • AftD plays a vital role in cell division and viability, highlighting its potential as a therapeutic target.

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