Structural and qualitative analysis of non-canonical PilZ domain proteins Xc1028 and Xc6012 from a Gram-negative phytopathogenic bacterium
| Autor: | Tso-Ning Li, 李佐寧 |
|---|---|
| Rok vydání: | 2012 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 100 The transition between planktonic and sessile lifestyle for bacteria is highly regulated. Recently, the bacteria-specific second messenger (3’–5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) was found to be critically involved in the switch from such transition, and PilZ domain be one of the key receptors for this important second messenger. Currently, many PilZ domain-containing proteins have been identified, and several tertiary structures of PilZ domains capable of binding c-di-GMP with strong affinity have been determined. Sequences of such PilZ domains feature a c-di-GMP signature. Here we have used X-ray crystallography to determine structures of two pathogenic proteins Xc1028 and Xc6012 form X. campestris strain 17. Both of them are PilZ-domain proteins however do not possess a complete c-di-GMP signature. Comparing to the typical PilZ domains, Xc1028 and Xc6012 adopt a similar tertiary structure, however, significant structural differences are detected at the N-terminus of these PilZ-domain containing proteins that exhibit substantial difference in the c-di-GMP binding activity. Xc6012 tetramer comprises a tetramerization domain stabilized by a 12-helices bundle containing a parallel four-stranded coiled-coil located in the center, and four PilZ domains pointing outward. We further generated a series of Xc6012 variants and measured the unfolding temperatures and oligomeric states in order to investigate the nature of this novel tetramer. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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