tailieunhanh - Expression analysis of genes in the nif cluster of Clostridium beijerinckii

The nif genes of Clostridium beijerinckii NRRL B593 occupy a region of about 16 kilobases. Besides the two glnB-like genes, five other genes are interspersed between the nifNB and the nifVω genes. | Turk J Biol 31 (2007) 7-11 © TÜB‹TAK Expression Analysis of Genes in the Nif Cluster of Clostridium beijerinckii 1,2 Murat KASAP 1 , Jiann-Shin CHEN 1 Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 USA 2 Department of Medical Biology, Kocaeli University Medical Center, 41380 Umuttepe, Kocaeli - TURKEY Received: Abstract: The nif genes of Clostridium beijerinckii NRRL B593 occupy a region of about 16 kilobases. Besides the two glnB-like genes, five other genes are interspersed between the nifNB and the nifVω genes. An expression analysis of the nif genes in nitrogenfixing and non-nitrogen-fixing cells with probes generated from various regions of the nif cluster by northern blot analysis revealed the presence of four different transcripts in nitrogen-fixing cells. Two of these transcripts had the predicted sizes spanning from nifH to nifK and from nifVω to nifVα, respectively. The other two transcripts did not have the expected sizes, but they suggested the presence of two other polycistronic mRNAs consisting of nifE-nifNB and nirJ1-nirJ2-nirD-nirH, respectively. The absence of the nif and nif-associated mRNAs in RNA samples from non-nitrogen-fixing cells indicated that nif-associated genes are regulated in parallel to nif genes. Key Words: Nitrogen fixation, transcriptional analysis, Clostridium beijerinckii, northern blotting, nif cluster Clostridium beijerinckii’da Bulunan Nif Genlerinin Ekspresyon Analizi Özet: Clostridium beijerinckii NRRL B593’de bulunan nif genleri 16 kilobaz çiflik bir bölgeyi kaplamaktad›r. Bilinen iki glnB benzeri genlerin yan›s›ra, befl adet farkl› gen nifNB ve nifVω aras›n› iflgal eder. Bu cal›flmada azot fiksasyonu yapan ve yapmayan iki farkl› C. beijerinckii kültür tipinde nif gen grubundan düzenlenen problarla yap›lan transkripsiyon analizinde dört farkl› transkripsiyonun azot fikse eden kültürlerde varl›¤› northern blot analizi ile gösterildi. Bu .