A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
A nested gene in Streptomyces bacteria encodes a protein involved in quaternary complex formation
Tekijät: Kallio P, Liu ZL, Mantsala P, Niemi J, Metsa-Ketela M
Kustantaja: ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD
Julkaisuvuosi: 2008
Tietokannassa oleva lehden nimi: JOURNAL OF MOLECULAR BIOLOGY
Lehden akronyymi: J MOL BIOL
Vuosikerta: 375
Numero: 5
Aloitussivu: 1212
Lopetussivu: 1221
Sivujen määrä: 10
ISSN: 0022-2836
DOI: https://doi.org/10.1016/j.jmb.2007.11.044
Tiivistelmä
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. (C) 2007 Elsevier Ltd. All rights reserved.
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. (C) 2007 Elsevier Ltd. All rights reserved.
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