The A 1 A o ATPase from Methanosarcina mazei : Cloning of the 5′ End of the aha Operon Encoding the Membrane Domain and Expression of the Proteolipid in a Membrane-Bound Form in Escherichia coli
| Autor: | Claudia Ruppert, Volker Müller, Thorsten Lemker, Sönke Wimmers |
|---|---|
| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | Journal of Bacteriology. 180:3448-3452 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.180.13.3448-3452.1998 |
| Popis: | Three additional ATPase genes, clustered in the order ahaH , ahaI , and ahaK , were found upstream of the previously characterized genes ahaECFABDG coding for the archaeal A 1 A o ATPase from Methanosarcina mazei . ahaH , the first gene in the cluster, is preceded by a conserved promoter sequence. Northern blot analysis revealed that the clusters ahaHIK and ahaECFABDG are transcribed as one message. AhaH is a hydrophilic polypeptide and is similar to peptides of previously unassigned function encoded by genes preceding postulated ATPase genes in Methanobacterium thermoautotrophicum and Methanococcus jannaschii . AhaI has a two-domain structure with a hydrophilic domain of 39 kDa and a hydrophobic domain with seven predicted transmembrane α helices. It is similar to the 100-kDa polypeptide of V 1 V o ATPases and is therefore suggested to participate in proton transport. AhaK is a hydrophobic polypeptide with two predicted transmembrane α helices and, on the basis of sequence comparisons and immunological studies, is identified as the proteolipid, a polypeptide which is essential for proton translocation. However, it is only one-half and one-third the size of the proteolipids from M. thermoautotrophicum and M. jannaschii , respectively. ahaK is expressed in Escherichia coli , and it is incorporated into the cytoplasmic membrane despite the different chemical natures of lipids from archaea and bacteria. This is the first report on the expression and incorporation into E. coli lipids of a membrane integral enzyme from a methanogens, which will facilitate analysis of the structure and function of the membrane domain of the methanoarchaeal ATPase. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|