Reviewed, UniProtKB/Swiss-Prot Q55274 (ISIA_SYNY3)

Names and origin

Protein names

Recommended name:
    Iron stress-induced chlorophyll-binding protein
Alternative name(s):
    CP43'

Gene names

Name:	isiA
Ordered Locus Names:	sll0247

Organism

Synechocystis sp. (strain PCC 6803) [Complete proteome] [HAMAP]

Taxonomic identifier

1148 [NCBI]

Taxonomic lineage

Bacteria › Cyanobacteria › Chroococcales › Synechocystis

Protein attributes

Sequence length	342 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Functions as an antenna for photosystem I (PSI) under iron-limiting conditions, when phycobilisomes disappear. In the (PSI)3(Isi3)18 complex most of the harvested energy is probably used by PSI; in other PSI-containing supercomplexes a large part of the energy will probably not be used for light harvesting, but rather is dissipated to protect the organism from light damage. Ref.6
Cofactor	Binds 16 chlorophyll a molecules per subunit Probable. Binds 2 beta-carotene molecules per subunit Probable. Bind 1 echinenone molecule per subunit Probable. Bind 1 zeaxanthin molecule per subunit Probable.
Subunit structure	Under iron-starvation forms a complex with PSI trimers, where the trimer is surrounded by a ring composed of 18 isiA subunits. When the PSI subunits psaF and psaJ are missing the ring is composed of 17 isiA subunits, indicating that each isiA subunit has a different interaction with the trimer. This suggests that the size of the PSI complex determines the number of IsiA units in the surrounding ring. In the absence of psaL has a tendency to form incomplete rings with PSI monomers, suggesting psaL helps form the rings. Also forms other aggregates of varying sizes depending on the level of iron-deprivation.
Subcellular location	Cellular thylakoid membrane; Multi-pass membrane protein Ref.6 Ref.5.
Induction	By iron stress, salt stress and to a lesser extent by heat shock. Ref.3
Sequence similarities	Belongs to the psbB/psbC family. IsiA/pcb subfamily.

Ontologies

Keywords
Biological process	Photosynthesis Stress response
Cellular component	Membrane Photosystem I Thylakoid
Domain	Transmembrane
Ligand	Chlorophyll Chromophore
Technical term	Complete proteome
Gene Ontology (GO)
Biological process	cellular response to iron ion starvation Inferred from direct assay. Source: UniProtKB photosynthetic electron transport chain Inferred from electronic annotation. Source: InterPro protein-chromophore linkage Inferred from electronic annotation. Source: UniProtKB-KW
Cellular component	integral to membrane Inferred from electronic annotation. Source: UniProtKB-SubCell plasma membrane-derived photosystem I Inferred from direct assay. Source: UniProtKB
Molecular function	chlorophyll binding Inferred from electronic annotation. Source: UniProtKB-KW identical protein binding Ref.7 Inferred from physical interaction. Source: IntAct
Complete GO annotation...

Binary interactions

With	Entry	#Exp.	IntAct	Notes
itself		1	EBI-597800,EBI-597800

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 342	342	Iron stress-induced chlorophyll-binding protein		PRO_0000077562
Regions
	Transmembrane	25 – 45	21	Potential
	Transmembrane	89 – 109	21	Potential
	Transmembrane	138 – 158	21	Potential
	Transmembrane	208 – 228	21	Potential
	Transmembrane	240 – 260	21	Potential
	Transmembrane	303 – 323	21	Potential
Experimental info
	Sequence conflict	94	1	S → R in AAA27291. Ref.1
	Sequence conflict	334 – 342	9	EQAFDSLQT → NKRLIPCKPSH in AAA27291. Ref.1

Sequences

	Sequence		Length	Mass (Da)
	Q55274-1 [UniParc]. Last modified November 1, 1997. Version 2. Checksum: 3510C9D4F6EADC4C	FASTA	342	37,221
	10 20 30 40 50 60 MQTYGNDTVQ YEWWAGNARF ADQSGLFIAA HVAQAALTAF WAGAFTLFEI SRFDPTQAMG 70 80 90 100 110 120 DQGLILLPHL ATLGWGVGDG GQIVDTYPYF VIGSIHLIAS AVLGAGALFH TLRAPADLST 130 140 150 160 170 180 LKGQGKKFHF TWENPQQLGI ILGHHLLFLG AGALLLAGKA MYWGGLYDAT TQTVRLVSQP 190 200 210 220 230 240 TLDPLVIYGY QTHFASISSL EDLVGGHIFV GFLLIGGGIW HILVPPLGWA KKVLLFSGEA 250 260 270 280 290 300 ILSYSLGGIA LAGFVAAYFC AVNTLAYPPE FYGPPLAIKL GIFPYFADTV ELPMHAHTSR 310 320 330 340 AWLANAHFFL AFFFLQGHLW HALRALGFDF KRVEQAFDSL QT

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"Sequence of isiS from Synechocystis PCC 6803." Ferreira F., Straus N.A. Submitted (DEC-1993) to the EMBL/GenBank/DDBJ databases Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
[2]	"Sequence analysis of the genome of the unicellular cyanobacterium Synechocystis sp. strain PCC6803. II. Sequence determination of the entire genome and assignment of potential protein-coding regions." Kaneko T., Sato S., Kotani H., Tanaka A., Asamizu E., Nakamura Y., Miyajima N., Hirosawa M., Sugiura M., Sasamoto S., Kimura T., Hosouchi T., Matsuno A., Muraki A., Nakazaki N., Naruo K., Okumura S., Shimpo S. , Takeuchi C., Wada T., Watanabe A., Yamada M., Yasuda M., Tabata S. DNA Res. 3:109-136(1996) [PubMed: 8905231] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
[3]	"Transcriptional analysis of the isiAB operon in salt-stressed cells of the cyanobacterium Synechocystis sp. PCC 6803." Vinnemeier J., Kunert A., Hagemann M. FEMS Microbiol. Lett. 169:323-330(1998) [PubMed: 9868777] [Abstract] Cited for: INDUCTION BY HIGH SALT AND IRON-DEFICIENCY.
[4]	"Iron deficiency induces the formation of an antenna ring around trimeric photosystem I in cyanobacteria." Bibby T.S., Nield J., Barber J. Nature 412:743-745(2001) [PubMed: 11507643] [Abstract] Cited for: STRUCTURAL ASSOCIATION WITH PHOTOSYSTEM I TRIMERS.
[5]	"Photosystem I trimers from Synechocystis PCC 6803 lacking the PsaF and PsaJ subunits bind an IsiA ring of 17 units." Kouril R., Yeremenko N., D'Haene S., Yakushevska A.E., Keegstra W., Matthijs H.C.P., Dekker J.P., Boekema E.J. Biochim. Biophys. Acta 1607:1-4(2003) [PubMed: 14556907] [Abstract] Cited for: SUBCELLULAR LOCATION, RING STRUCTURE IN THE ABSENCE OF PSAF AND PSAJ.
[6]	"Aggregates of the chlorophyll-binding protein IsiA (CP43') dissipate energy in cyanobacteria." Ihalainen J.A., D'Haene S., Yeremenko N., van Roon H., Arteni A.A., Boekema E.J., van Grondelle R., Matthijs H.C.P., Dekker J.P. Biochemistry 44:10846-10853(2005) [PubMed: 16086587] [Abstract] Cited for: SUBCELLULAR LOCATION, PIGMENT ANALYSIS, FUNCTION IN LIGHT PROTECTION.
[7]	"Supercomplexes of IsiA and photosystem I in a mutant lacking subunit PsaL." Kouril R., Yeremenko N., D'Haene S., Oostergetel G.T., Matthijs H.C.P., Dekker J.P., Boekema E.J. Biochim. Biophys. Acta 1706:262-266(2005) [PubMed: 15694354] [Abstract] Cited for: RING STRUCTURE IN THE ABSENCE OF PSAL.
[8]	"Structure and functional role of supercomplexes of IsiA and Photosystem I in cyanobacterial photosynthesis." Kouril R., Arteni A.A., Lax J., Yeremenko N., D'Haene S., Rogner M., Matthijs H.C., Dekker J.P., Boekema E.J. FEBS Lett. 579:3253-3257(2005) [PubMed: 15943969] [Abstract] Cited for: REVIEW.

Cross-references

Sequence databases
EMBLGenBankDDBJ	L26530 Genomic DNA. Translation: AAA27291.1. BA000022 Genomic DNA. Translation: BAA17948.1.
PIR	S75086.
RefSeq	NP_441268.1.
3D structure databases
ModBase	Search...
Protein-protein interaction databases
IntAct	Q55274. 6 interactions.
STRING	Q55274.
Genome annotation databases
GeneID	954611.
GenomeReviews	Gene locus sll0247 in contig BA000022_GR.
KEGG	syn:sll0247.
NMPDR	fig|1148.1.peg.1369.
Organism-specific databases
CMR	Search...
Phylogenomic databases
HOGENOM	HBG284351.
OMA	GIVVICT.
Enzyme and pathway databases
BioCyc	SSP1148:SLL0247-MON.
Family and domain databases
InterPro	IPR000932. PS_antenna-like. [Graphical view]
Pfam	PF00421. PSII. 2 hits. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

ISIA_SYNY3

Accession

Primary (citable) accession number: Q55274
Secondary accession number(s): P73884

Entry history

Integrated into UniProtKB/Swiss-Prot:	November 1, 1997
Last sequence update:	November 1, 1997
Last modified:	December 15, 2009
This is version 64 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HAMAP (High-quality Automated and Manual Annotation of microbial Proteomes)