Schiefer Wolfgang, Schütz Kathrin, Hachtel Wolfgang, Happe Thomas
Botanisches Institut, Universität Bonn, Karlrobert-Kreiten-Strasse 13, 53115 Bonn, Germany.
Biochim Biophys Acta. 2002 Aug 19;1577(1):139-43. doi: 10.1016/s0167-4781(02)00399-8.
HetR, a serine type protease, plays an important role in heterocyst differentiation in filamentous cyanobacteria. We isolated and sequenced the hetR genes from different heterocystous and filamentous nonheterocystous cyanobacteria. The hetR gene in the heterocyst forming Anabaena variabilis ATCC 29413 FD was interrupted by interposon mutagenesis (mutant strain WSIII8). This mutant does not form heterocysts and shows no diazotrophic growth under aerobic conditions. However, under anaerobic N(2)-fixing conditions, the WSIII8 cells are able to grow, and high nitrogenase (Nif2) activity is detectable. Nif2 expression was demonstrated in each vegetative cell of the filament by immunolocalization 4 h after nitrogen step-down.
HetR是一种丝氨酸型蛋白酶，在丝状蓝细菌的异形胞分化中起重要作用。我们从不同的异形胞和丝状非异形胞蓝细菌中分离并测序了hetR基因。在形成异形胞的多变鱼腥藻ATCC 29413 FD中，hetR基因被转座子诱变打断（突变株WSIII8）。该突变体不形成异形胞，在有氧条件下不显示固氮生长。然而，在厌氧固氮条件下，WSIII8细胞能够生长，并且可检测到高固氮酶（Nif2）活性。在氮源减少4小时后，通过免疫定位在丝状体的每个营养细胞中证实了Nif2的表达。
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