Crystal structure and mutagenic analysis of a bacteriocin immunity protein,Mun-im |
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| Authors: | Hyung Joon Jeon Masafumi Noda Yasuyuki Matoba Takanori Kumagai Masanori Sugiyama |
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| Institution: | 1. Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA;2. Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697, USA;3. Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA 92697, USA;4. Biomolecular Science and Engineering Program, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA |
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| Abstract: | Bacteriocin-producing lactic acid bacteria (LAB) possess a self-protection factor, which is generally called an immunity protein. In this study, we determine the crystal structure of an immunity protein, designated Mun-im, which was classified into subgroup B immunity proteins for class IIa bacteriocins. The Mun-im protein takes a left-turning antiparallel four-helix bundle structure with the flexible N- and C-terminal parts. Although the amino acid sequences of the subgroup B immunity proteins are distinguished from those of the subgroup A, the core structure of Mun-im is well-superimposed with that of the subgroup A immunity protein, EntA-im, and the C-terminus of both proteins is flexible. However, the C-terminus of Mun-im is obviously shorter than that of the subgroup A. We found through mutagenic study of Mun-im that the C-terminus and the K86 residue on the helix 4 in the immunity protein molecule are important for expression of the immunity activity on the subgroup B immunity proteins. |
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