Annotations: 4HH3

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
C	EUF07998	e4hh3C4	A: alpha arrays	X: Methionine synthase domain-like (From Topology)	H: Methionine synthase domain-like (From Topology)	T: Methionine synthase domain-like	F: EUF07998	ECOD (1.6)
C	UNK_F_TYPE	e4hh3C2	A: a/b three-layered sandwiches	X: Flavodoxin-like	H: Class I glutamine amidotransferase-like	T: CheY-like	F: UNK_F_TYPE	ECOD (1.6)
B	PAS	e4hh3B3	A: a+b three layers	X: Profilin-like	H: sensor domains (From Topology)	T: sensor domains	F: PAS	ECOD (1.6)
B	UNK_F_TYPE	e4hh3B4	A: a+b three layers	X: Profilin-like	H: sensor domains (From Topology)	T: sensor domains	F: UNK_F_TYPE	ECOD (1.6)
A	PAS	e4hh3A1	A: a+b three layers	X: Profilin-like	H: sensor domains (From Topology)	T: sensor domains	F: PAS	ECOD (1.6)
A	UNK_F_TYPE	e4hh3A2	A: a+b three layers	X: Profilin-like	H: sensor domains (From Topology)	T: sensor domains	F: UNK_F_TYPE	ECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
C	1.10.1240.10	Mainly Alpha	Orthogonal Bundle	Methyltransferase, Methionine Synthase (B12-binding Domains)	Chain A, domain 1	CATH (4.2.0)
C	3.40.50.280	Alpha Beta	3-Layer(aba) Sandwich	Rossmann fold	Cobalamin-binding domain	CATH (4.2.0)
B	3.30.450.20	Alpha Beta	2-Layer Sandwich	Beta-Lactamase	PAS domain	CATH (4.2.0)
A	3.30.450.20	Alpha Beta	2-Layer Sandwich	Beta-Lactamase	PAS domain	CATH (4.2.0)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
C	PF21961	AppA, four helix bundle (AppA_4HB)	AppA, four helix bundle	This domain is found in AppA protein from Rhodobacter sphaeroides and similar sequences from alphaproteobacteria. AppA is a light -sensing antirepressor involved in oxygen and light control of photosynthesis-gene expression. This protein senses blue- ...	This domain is found in AppA protein from Rhodobacter sphaeroides and similar sequences from alphaproteobacteria. AppA is a light -sensing antirepressor involved in oxygen and light control of photosynthesis-gene expression. This protein senses blue-light via its N-terminal sensor of blue-light using FAD (BLUF) domain (Pfam:PF04940) and oxygen via its SCHIC (sensor containing heme instead of cobalamin) domain. This entry represents the domain that locates in between them, which folds as a four helix bundle (4HB) and acts as a binding platform for the adjacent domains [1-2].	Domain
C	PF21966	AppA, sensor containing heme instead of cobalamin (AppA_SCHIC)	AppA, sensor containing heme instead of cobalamin	This domain is found at the C-terminal end of AppA protein from Rhodobacter sphaeroides and similar sequences from alphaproteobacteria. AppA is a light-sensing antirepressor involved in oxygen and light control of photosynthesis-gene expression. This ...	This domain is found at the C-terminal end of AppA protein from Rhodobacter sphaeroides and similar sequences from alphaproteobacteria. AppA is a light-sensing antirepressor involved in oxygen and light control of photosynthesis-gene expression. This protein senses blue-light via its N-terminal blue-light using FAD (BLUF) domain (Pfam:PF04940) and oxygen via its sensor containing heme instead of cobalamin (SCHIC) domain (this entry). This domain has a flavodoxin-like fold [1,2].	Domain
A, B	PF13426	PAS domain (PAS_9)	PAS domain	This domain is found in many signalling proteins in which it functions as a sensor domain. It recognises FMN, Zn(II), FAD and riboflavin (MAtilla et. al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).	Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
C	AppA protein	blue light photoreceptor activity molecular transducer activity photoreceptor activity signaling receptor activity FAD binding flavin adenine dinucleotide binding binding nucleoside phosphate binding ion binding anion binding nucleotide binding heterocyclic compound binding small molecule binding	-	-
A, B	Transcriptional regulator, PpsR	sequence-specific DNA binding DNA binding binding nucleic acid binding identical protein binding protein binding	-	-

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
C	IPR007024	BLUF domain	Domain
C	IPR054140	AppA, four helical bundle	Domain
C	IPR054142	AppA, SCHIC domain	Domain
C	IPR036046	Acylphosphatase-like domain superfamily	Homologous Superfamily
C	IPR036594	Methionine synthase domain	Homologous Superfamily
A, B	IPR035965	PAS domain superfamily	Homologous Superfamily
A, B	IPR009057	Homedomain-like superfamily	Homologous Superfamily
A, B	IPR011785	Transcription regulator PpsR	Family
A, B	IPR000014	PAS domain	Domain
A, B	IPR002197	DNA binding HTH domain, Fis-type	Domain

RCSB PDB Core Operations are funded by the U.S. National Science Foundation (DBI-2321666), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM157729.