Showing papers by "Fernando Ferreira published in 1994"
TL;DR: This paper is intended as a review of molecular and physiological responses of actively growing cyanobacterial cultures to conditions of iron stress, where iron is present but essentially insoluble, and to differentiate these responses from iron starvation, where the amount of iron in the system is not sufficient for cell growth.
Abstract: Iron is an essential component of electron transport in almost all living organisms It is particularly important to phototrophs like cyanobacteria because 22–23 irons are required for a complete functional photosynthetic apparatus Since the low solubility of Fe+++ above neutral pH in oxic ecosystems severely limits the biological availability of iron to aquatic microorganisms, cyanobacteria and other microbes have developed a number of responses to cope with iron deficiency Cyanobacterial responses to iron stress include the synthesis of an efficient, siderophore-based system to scavenge iron and the substitution of ferredoxin with flavodoxin An additional response in cyanobacteria involves the alteration of the light-harvesting apparatus that includes the appearance of a new, iron-stress-induced, photosystem II, chlorophyll-binding protein Although cytochromec-553 has a potential non-iron-containing replacement in plastocyanin, a copper-containing protein, iron stress appears to favor the utilization of cytochromec-553 because siderophores also bind copper and form a complex that is excluded from the cell This paper is intended primarily as a review of molecular and physiological responses of actively growing cyanobacterial cultures to conditions of iron stress, where iron is present but essentially insoluble, and to differentiate these responses from iron starvation, where the amount of iron in the system is not sufficient for cell growth
101 citations
TL;DR: RNA transcript analyses indicate that the expression of the genes for cytochrome c-553 (petJ) and plastocyanin (petE) are regulated in reciprocal ways in response to copper concentration.
Abstract: In some cyanobacteria and eukaryotic algae, cytochrome c-553 (c-552) and plastocyanin function as alternative electron carriers between the cytochrome b6-f complex and Photosystem I. In these organisms plastocyanin is the electron carrier under copper-replete conditions, and cytochrome c-553 is the electron carrier during copper deprivation. In this paper we report the cloning, sequencing and transcriptional analysis of the genes for cytochrome c-553 and plastocyanin from Anabaena sp. PCC 7120. The gene for cytochrome c-553 encodes a preprotein containing 111 amino acids with a predicted n-terminal transit peptide sequence of 25 amino acids. The gene for plastocyanin encodes a preprotein containing 139 amino acids with a n-terminal transit peptide sequence of 34 amino acids. RNA transcript analyses indicate that the expression of the genes for cytochrome c-553 (petl) and plastocyanin (petE) are regulated in reciprocal ways in response to copper concentration. In copper-replete conditions, petJ is expressed at very low levels, but is transcribed at high levels under copper deprivation; petE is down-regulated in the absence of copper, but is rapidly up-regulated when copper is added back to the medium.
45 citations