کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2187506 | 1096123 | 2008 | 10 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: A Nested Gene in Streptomyces Bacteria Encodes a Protein Involved in Quaternary Complex Formation A Nested Gene in Streptomyces Bacteria Encodes a Protein Involved in Quaternary Complex Formation](/preview/png/2187506.png)
The gene pgaM is involved in the biosynthesis of an angucycline-type polyketide antibiotic in Streptomyces sp. PGA64. It encodes a two-domain polypeptide consisting of an N-terminal flavoprotein oxygenase and a C-terminal short-chain alcohol dehydrogenase/reductase, which are fused together at the translational level as a result of end codon deletion. Here we show that translation also initiates at an internal start codon that enables independent expression of a separate reductase subunit, PgaMred. This confirms that the gene exhibits a rare viral-like arrangement of two overlapping reading frames that allows simultaneous expression of two alternative forms of the protein. Together, these two proteins associate to form a stable non-covalent complex, the native form of PgaM. The reductase subunit PgaMred is shown to provide enzyme stability and to affect the redox state of the oxygenase domain FAD. Finally, a model for the quaternary structure of the complex that explains the necessity for a nested gene system and the unusual behaviour of the protein subunits in vitro is presented.
Journal: Journal of Molecular Biology - Volume 375, Issue 5, 1 February 2008, Pages 1212–1221