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Biochim Biophys Acta Proteins Proteom. 2017 Jan;1865(1):55-64. doi: 10.1016/j.bbapap.2016.10.011. Epub 2016 Oct 23.

Insight into the 3D structure and substrate specificity of previously uncharacterized GNAT superfamily acetyltransferases from pathogenic bacteria.

Author information

1
Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA; Center for Structural Genomics of Infectious Diseases (CSGID).
2
Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA 94132, USA.
3
Northwestern University Feinberg School of Medicine, Department of Molecular Pharmacology and Biological Chemistry, Chicago, IL 60611, USA; Center for Structural Genomics of Infectious Diseases (CSGID).
4
Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA; Center for Structural Genomics of Infectious Diseases (CSGID). Electronic address: wladek@iwonka.med.virginia.edu.
5
Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA 94132, USA. Electronic address: mkuhn@sfsu.edu.

Abstract

Members of the Gcn5-related N-acetyltransferase (GNAT) superfamily catalyze the acetylation of a wide range of small molecule and protein substrates. Due to their abundance in all kingdoms of life and diversity of their functions, they are implicated in many aspects of eukaryotic and prokaryotic physiology. Although numerous GNATs have been identified thus far, many remain structurally and functionally uncharacterized. The elucidation of their structures and functions is critical for broadening our knowledge of this diverse and important superfamily. In this work, we present the structural and kinetic analyses of two previously uncharacterized bacterial acetyltransferases - SACOL1063 from Staphylococcus aureus strain COL and CD1211 from Clostridium difficile strain 630. Our structures of SACOL1063 show substantial flexibility of a loop that is likely responsible for substrate recognition and binding compared to structures of other homologs. In the CoA complex structure, we found two CoA molecules bound in both the canonical AcCoA/CoA-binding site and the acceptor-substrate-binding site. Our work also provides initial clues regarding the substrate specificity of these two enzymes; however, their native function(s) remain unknown. We found both proteins act as N- rather than O-acetyltransferases and preferentially acetylate l-threonine. The combination of structural and kinetic analyses of these two previously uncharacterized GNATs provides fundamental knowledge and a framework on which future studies can be built to elucidate their native functions.

KEYWORDS:

Acetyltransferase; Amino acid acetylation; GNAT; Gcn5-related N-acetyltransferase; Serine and threonine acetylation

PMID:
27783928
PMCID:
PMC5127773
DOI:
10.1016/j.bbapap.2016.10.011
[Indexed for MEDLINE]
Free PMC Article

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