Consequences of the iron-dependent formation of ferredoxin and flavodoxin on photosynthesis and nitrogen fixation on Anabaena strains

Abstract

Iron-dependent formation of ferredoxin and flavodoxin was determined in Anabaena ATCC 29413 and ATCC 29211 by a FPLC procedure. In the first species ferredoxin is replaced by flavodoxin at low iron levels in the vegetative cells only. In the heterocysts from Anabaena ATCC 29151, however, flavodoxin is constitutively formed regardless of the iron supply.Replacement of ferredoxin by flavodoxin had no effect on photosynthetic electron transport, whereas nitrogen fixation was decreased under low iron conditions. As ferredoxin and flavodoxin exhibited the same Km values as electron donors to nitrogenase, an iron-limited synthesis of active nitrogenase was assumed as the reason for inhibited nitrogen fixation. Anabaena ATCC 29211 generally lacks the potential to synthesize flavodoxin. Under iron-starvation conditions, ferredoxin synthesis is limited, with a negative effect on photosynthetic oxygen evolution.

Quantitative analysis of iron-stress related proteins in Thalassiosira weissflogii:measurement of flavodoxin and ferredoxin using HPLC

“…A promising direction is suggested by a survey of the bacterial and cyanobacterial literature, which indicates that a common response to iron stress among prokaryotes is to reduce levels of ferredoxin (Fd), an evolutionarily conserved non-heme, iron-sulfur protein, while turning on production of flavodoxin (Flv), a flavoprotein capable of catalyzing many of the same reactions as Fd yet requiring no iron for its biosynthesis (e.g. Knight & Hardy 1966, Hutber et al 1977, Drummond 1985, Sandmann et al 1990. While the production of Flv is frequently induced only by decreasing levels of iron bioavailability, certain prokaryotes can also synthesize this flavoprotein constitutively (Vetter & Knappe 1971, Klugkist et al 1986).…”

“…Furthermore, the separation chemistry can be applied to preparative scale samples in order to purify compounds for additional work such as chemical characterization or antibody production. Although liquid chromatography methods for Flv (and Fd) have been reported (Fish & Sanders-Loehr 1987, Jones 1988, Sandmann et al 1990), all rely on the technique of fast protein liquid chromatography (FPLC) and require specialized equipment apart from conventional HPLC components. Our aim, therefore, was to develop an HPLC protocol for the separation and identification of Flv and Fd based on FPLC methods established previously for these proteins.…”

Characterization of ferredoxin and flavodoxin as molecular indicators of iron limitation in marine eukaryotic phytoplankton

“…induces flavodoxin when iron-limited (Fillat et al 1988), Anabaena ATCC292J1 does not produce flavodoxin (Pardo et al 1990), while Anabaena ATCC29151 produces flavodoxin constitutively in its heterocysts (Sandmann et al 1990). The cyanobacteria Synechocystis (Bottin & Lagoutte 1992) and Anacystis nidulans , and the green alga Chlorella fusca are all known to induce flavodoxin when iron-limited.…”

“…It has been reported to be both more and less efficient than ferredoxin in electron transfer, depending upon the reaction being studied (e.g. , Sandmann et al 1990, Razquin et al 1995. Like ferredoxin, it is water soluble and present in the chloroplast stroma.…”

“…There exists some heterogeneity in response, as not all organisms examined produce flavodoxin while some induce it under iron limitation and others express it constitutively. Various strains of the freshwater cyanobacterium Anabaena show three different modes of induction: Anabaena ATCC29413 induces flavodoxin when iron-limited (Fillat et al 1988), Anabaena ATCC29211 does not produce flavodoxin (Pardo et al 1990), while Anabaena ATCC29151 produces flavodoxin constitutively in its heterocysts (Sandmann et al 1990). …”