TITLE

High resolution crystal structure of PedB: a structural basis for the classification of pediocin-like immunity proteins

AUTHOR(S)
In-Kwon Kim; Min-Kyu Kim; Ji-Hye Kim; Hyung-Soon Yim; Sun-Shin Cha; Sa-Ouk Kang
PUB. DATE
January 2007
SOURCE
BMC Structural Biology;2007, Vol. 7, p35
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Background: Pediocin-like bacteriocins, ribosomally-synthesized antimicrobial peptides, are generally coexpressed with cognate immunity proteins in order to protect the bacteriocin-producer from its own bacteriocin. As a step for understanding the mode of action of immunity proteins, we determined the crystal structure of PedB, a pediocin-like immunity protein conferring immunity to pediocin PP-1. Results: The 1.6 Ã… crystal structure of PedB reveals that PedB consists of an antiparallel four-helix bundle with a flexible C-terminal end. PedB shows structural similarity to an immunity protein against enterocin A (EntA-im) but some disparity to an immunity protein against carnobacteriocin B2 (ImB2) in both the C-terminal conformation and the local structure constructed by a3, a4, and their connecting loop. Structure-inspired mutational studies reveal that deletion of the last seven residues of the C-terminus of PedB almost abolished its immunity activity. Conclusion: The fact that PedB, EntA-im, and ImB2 share a four-helix bundle structure strongly suggests the structural conservation of this motif in the pediocin-like immunity proteins. The significant difference in the core structure and the C-terminal conformation provides a structural basis for the classification of pediocin-like immunity proteins. Our mutational study using C-terminal-shortened PedBs and the investigation of primary sequence of the C-terminal region, propose that several polar or charged residues in the extreme C-terminus of PedB which is crucial for the immunity are involved in the specific recognition of pediocin PP-1.
ACCESSION #
29323596

 

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