碩士 / 國立中興大學 / 生命科學系所 / 95 / The osmoregulated primary and secondary transporters for osmolytes as proline, choline and glycine betaine in response to the salt and osmotic stress are common in Bacteria and Archaea. However, few investigations related to the osmolyte transporters in Archaea have been reported. The primary glycine betaine transporters driven by ATP hydrolysis in Methanohalophilus portucalensis strain FDF1 and Methanosarcina mazei Göe1 have been investigated and were both responsed with salt stress. Whereas, only one secondary glycine betaine transporter driven by ion gradient in Methanosarcina thermophila TM-1 have been discussed. In this study, a slightly halophilic methanogen Methanosarcina mazei N2M9705 was used to survey the secondary osmolyte transporters. Base on the annoated Na+/proline transporter sequence of Methanosarcina mazei Göe1, the specific primers were designed for PCR amplification of putP of strain N2M9705. The amplified fragment was further purified, cloned and sequenced which contains 1917 bp with G+C ratio at 47.7 %. The putP of strain N2M9705 could be translated into 639 aa polypeptide with molecular weight of 68,880 and the isoelectric point is 5.9. The amino acid similarity of PutP was 99.8 % identity with Na+/proline transporter of Methanosarcina mazei Göe1. Amino acids analysis showed that, like a member of the sodium solute symporter family (SSSF), PutP posses 13 transmembrane regions, and the SSSF signature 2 (NA_SOLUT_SYMP_2; PS00457) is located between amino acids 419 ~ 439. The amino acids of Arg-40 and Asp-187 of Na+/proline transporter system PutP of E. coli is participating the coupling of ion and may involve the release of sodium on cytoplasmic side of the membrane. There were conserved Arg-40 and Asp-179 in PutP of strain N2M9705. However, amino acid comparison suggests the low affinity of proline binding of PutPN2M which indicated the possibility of other solutes as the partner of this sodium dependent secondary transporter.
| Identifer | oai:union.ndltd.org:TW/095NCHU5105025 |
| Date | January 2007 |
| Creators | Yu-Zhen Zhang, 張鈺甄 |
| Contributors | 賴美津 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 70 |
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