Structure and Functional studies of Arginine Glycosyltransferases in P…

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  • Writer 최고관리자
  • 2017-12-21


[2017 Fall Life Sciences & IBB  Seminar]

▶Subject: Structure and Functional studies of Arginine Glycosyltransferases in Pathogenic Bacteria

▶Speaker: Prof. Hyun-Soo Cho (Yonsei University)
▶Date: 4:30PM/Dec. 22 (Fri.)/2017
▶Place: Auditorium(1F), POSTECH Biotech Center
▶Abctract: Homo- or hetero-oligomerization between death domains plays a key role in apoptosis and inflammation responses. TRADD and FADD have death domains which serve as adaptor proteins in TNF alpha-mediated NF-κB signaling. The bacterial effector protein SseK and NleB are glycosyltransferases that disrupt interactions between these death domain proteins of the host cell by transferring the sugar moiety onto a key residue and suppressing expression of NF-κB. Surprisingly, the glycosylation target residue is an arginine instead of the canonical O-glyosylation residues (serine and threonine) or the N-glycosylation residue (asparagine). This glycosylation is unlikely to be expected because the guanidine group of arginine is known to be chemically stable. Until now, this unique glycosylation is highly elusive in terms of enzymatic mechanism. Here, we report the crystal structures of SseK1, SseK2 from Salmonella typhimurium and NleB2 from Escherichia coli O145:H28. SseK and NleB are orthologue proteins and we have identified the catalytically important residues which are well conserved in all of the SseK and NleB families. In addition, substrate-mediated enzyme dynamics were demonstrated by X-ray crystallographic snapshots of intermediate states. Our results suggest the catalytic mechanism on how arginine can be glycosylated under atomic level.