Biology Reference
In-Depth Information
CHAPTER THREE
Iron in Cyanobacteria
Chana Kranzler
*
,
1
, Mareike Rudolf
†
,
1
, Nir Keren
*
,
2
, Enrico Schleiff
†
*Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences,
Edmond J. Safra Campus, Givat Ram, Hebrew University of Jerusalem, Jerusalem, Israel
†
Department of Biosciences, Molecular Cell Biology of Plants, Goethe-University, Frankfurt, Germany
1
The two authors contributed equally to this chapter.
2
Corresponding author: E-mail: nir@ke@mail.huji.ac.il
Contents
1. Iron Biogeochemistry in Water Bodies
58
1.1. Iron Chemistry and the Evolution of Oxygen Evolution
58
1.2. The Iron Hypothesis
59
1.3. Forms of Bioavailable Iron
60
2. Iron Uptake
61
2.1. Siderophores in Cyanobacteria
61
2.2. Siderophore Synthesis
65
2.3. Siderophore Export and Uptake Cycles
67
2.4. Siderophore Transport across the Periplasm and the Plasma Membrane
71
2.5. The Relation between Siderophore Iron Uptake and Copper Uptake
73
2.6. Reductive Iron Uptake
74
2.6.1. Non-siderophore-mediated Fe uptake
74
2.6.2. Uptake of free, unchelated, inorganic iron
75
2.6.3. Reductive siderophore uptake
77
2.7. Fe
′
Transport through the Plasma Membrane
78
2.8. Environmental Implications
78
3. Intracellular Fe Homeostasis
79
4. Iron-Dependant Gene Regulation and Physiological Responses
82
4.1. Regulation of Cyanobacterial Gene Expression by Iron
82
4.1.1. FurA - a regulator of global transcription?
86
4.1.2. FurB and FurC
87
4.1.3. Communication between the Cyanobacterial Fur and NtcA Systems
88
4.2. Iron-Dependant Regulation of Transcription by Antisense RNA
89
4.3. Physiological Responses
90
4.3.1. The IsiA Protein
91
4.3.2. The Flavodoxin IsiB
92
4.3.3. IdiABC
93
Abstract
Approximately 40% of global photosynthesis is conducted by phytoplankton in aquatic
environments. Cyanobacteria, Gram-negative photoautotrophic prokaryotes, contribute
