nifV is contiguous to nifHDK in Frankia strain FaC1 |
| |
Authors: | Bo Si Oh Paul G. Twigg Jeong Soo Hong Beth C. Mullin Chung Sun An |
| |
Affiliation: | Dept of Biology, Seoul National Univ., Seoul 151–742, Korea;Dept of Biology, Univ. of Nebraska at Kearney, Kearney, NE 68849, USA;Dept of Botany and the Center for Legume Research, The Univ. of Tennessee, Knoxville, TN 37996, USA |
| |
Abstract: | The organization of genes with the capacity to code for four proteins involved in nitrogen fixation in Frankia strain FaC1 was determined by restriction fragment mapping and nucleotide sequence analysis. Analysis of the 44-kb genomic cosmid clone pFAH 1. isolated from a cosmid library made from Frankia strain FaCl, resulted in the identification of a 7.2-kb Pst I fragment to which Klebsiella nif H, nif D and nif K probes hybridized. This nif -hybridizing fragment was subcloned and analyzed by restriction fragment mapping. Further subcloning of the 7.2-kb fragment and subsequent sequence analysis of approximately 6.8 kb revealed the presence of six open reading frames (ORFs). Four of these ORFs have the potential to code for nif V-, nif H-, nif D- and nif K-like gene products and the two others are unidentified ORFs. The organization of the structural genes for nitrogenase is the same in this Frankia strain as it is in most other nitrogen-fixing prokaryotes, but the positioning of the nif V-like gene relative to the nif HDK cluster differs, A consensus nif -promoter-like sequence, found 5'to nif H. was not detected upstream of the nif V-like gene. Nine copies of a 7-bp direct repeat were found 5'to ORFA. |
| |
Keywords: | Directly repeated sequence Frankia strain FaCl homocitrate synthase nifD nifH nifK nifV nif-organization |
|
|