Biology Reference
In-Depth Information
CHAPTER ONE
Structural, Mechanistic
and Genomic Insights into
OCP-Mediated Photoprotection
Cheryl A. Kerfeld
†
,
§
,
1
, Diana Kirilovsky
‡
†
United States Department of Energy Joint Genome Institute, Walnut Creek, California, USA
§
Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
‡
Laboratoire de Mécanismes fondamentaux de la bioénergie, UMR8221, CEA Saclay, Gif-sur-Yvette, France
1
Corresponding author: E-mail: ckerfeld@lbl.gov
Contents
1. Introduction
2
2. TheOCP-BasedNPQMechanismisPhotoprotective
4
2.1. InitialObservations
4
2.2. TheOCPInducesaDecreaseoftheEfectiveAntennaSize
5
3. OCP-MediatedPhotoprotectionfromaStructuralPerspective
6
3.1. CrystalStructuresoftheOCP
6
3.2. CluestotheStructuralBasisofPhotoactivity
7
3.3. StructuralSimilaritiestoOtherBlue-Light-ResponsiveProteins
11
4. TheOCP-PhycobilisomeInteraction
11
4.1. The
In Vitro
ReconstitutionSystem:OnlyOCP
r
InteractsWithPhycobilisomes
11
4.2. TheSiteofEnergyandFluorescenceQuenchinginthePhycobilisomeCore
12
4.3. WhatPartoftheOCPInteractswiththePhycobilisome?
15
5. DiscoveryandCharacterizationoftheFluorescenceRecoveryProtein
16
6. InsightsfromGenomicDistributionofComponentsoftheOCPPhotoprotective
Mechanism
17
6.1. DistributionofGenesEncodingtheOCP
17
6.2. DistributionofGenesEncodingtheFRP
20
7. AModelfortheOCP-MediatedPhotoprotectiveMechanism
20
8. OutstandingQuestionsandFutureProspects
22
Abstract
Until relatively recently, photoprotective mechanisms in cyanobacteria were poorly
understood.Yet, they play a crucial role in the ecophysiology of cyanobacteria, which
inhabitarangeofenvironments,someofthemareextremewherestressessuchashigh
salinity, drought and temperature exacerbate the threat of photodamage. This review
focusesontheOCP-mediatedphotoprotectivemechanism,whichiswidespreadamong
cyanobacteria. Mechanistic and structural studies combined with genomic sequence
dataarepaintinganincreasinglydetailedpictureofOCP-mediatedphotoprotection.
