Associate Professor CHNG Shu Sin

(Assistant Head - Research & Education)




B.Sc. (Hons), National University of Singapore, 2000-2003; Ph.D., Harvard University, 2004-2010; Postdoctoral fellow, Harvard Medical School, 2010-2011.

Contact Information

Office: MD1-14-03C
Tel: (65)-6516-2682 | Fax: (65)-6779-1691
Email: chmchngs@nus.edu.sg


 

ORCID: 0000-0001-5466-7183
ResearcherID: B-1759-2018

 

Recognition and Achievements

  • NUS Annual Excellence Teaching Award 2013/14 and 2014/15
  • NUS Faculty Excellence Teaching Award 2013/14, 2014/15 and 2015/16
  • Shortlisted for Singapore National Academy of Science (SNAS) Young Scientist Award, 2014
  • Christensen Prize for outstanding research achievement, 2009

 

Research Interests

My group focuses on understanding how biological membranes are assembled in cells using bacterial outer membranes as models. Specifically, we are interested to elucidate the mechanisms of inter-membrane lipid trafficking in Gram-negative bacteria and mycobacteria and to identify protein targets in these bacteria for antibiotics discovery.

 

Research Highlight

The defining feature of the mycobacterial outer membrane (OM) is the presence of mycolic acids (MAs), which in part render the bilayer extremely hydrophobic and impermeable to external insults, including many antibiotics. While the biosynthetic pathway of MAs is well studied, the mechanism(s) by which these lipids are transported across the cell envelope is(are) much less known. MmpL3, an essential inner membrane (IM) protein, is implicated in MA transport, but its exact function has not been elucidated. It is believed to be the cellular target of several anti-mycobacterial compounds; however, evidence for direct inhibition of MmpL3 activity is also lacking. Here, we establish that MmpL3 is the MA flippase at the IM of mycobacteria, and is the molecular target of BM212, a 1,5-diarylpyrrole compound. We develop assays that selectively access mycolates on the surface of Mycobacterium smegmatis spheroplasts, allowing us to monitor flipping of MAs across the IM. Using these assays, we establish the mechanism-of-action of BM212 as a potent MmpL3 inhibitor, and employ it as a molecular probe to demonstrate the requirement for functional MmpL3 in the transport of MAs across the IM. Finally, we show that BM212 binds MmpL3 directly and inhibits its activity. Our work provides fundamental insights into OM biogenesis and MA transport in mycobacteria. Furthermore, our assays serve as an important platform for accelerating the validation of small molecules that target MmpL3, and their development as future anti-tuberculosis drugs.

 

Teaching Contributions   

  • CM3225 Biomolecules
  • CM4227 Chemical Biology

 

Representative Publications   

  • Shrivastava, R.; Jiang, X. E.; Chng, S.-S. Bacterial Outer Membrane Homeostasis via Retrograde Phospholipid Transport in Escherichia Coli. Mol. Microbiol. 2017, 106, 395-405.
  • Xu, Z. J.; Meshcheryakov, V. A.; Poce, G.; Chng, S.-S. MmpL3 is the Flippase for Mycolic Acids in Mycobacteria. Proc. Natl. Acad. Sci. U.S.A. 2017, 114, 7993-7998.
  • Thong, S. H.; Ercan, B.; Torta, F.; Fong, Z. Y.; Wong, H. Y.; Wenk, M.R.; Chng, S.-S. Defining Key Roles for Auxiliary Proteins in an ABC Transporter that Maintains Bacterial Outer Membrane Lipid Asymmetry. eLife 2016, 5, e19042.
  • Chong, Z.-S.; Woo, W.-F.; Chng, S.-S. Osmoporin OmpC Forms a Complex with MlaA to Maintain Outer Membrane Lipid Asymmetry in Escherichia Coli. Mol. Microbiol. 2015, 98, 1133-1146.