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3.A.1.107.3
CcmABCD exporter; CcmD (69aas, 1TMS) is required for the release of CcmE (which binds heme in the periplasm) from CcmABC. CcmC (9.B.14.2.3) is required for the transfer of heme to CcmE in the periplasm (Richard-Fogal et al., 2008) In the presence of heme, CcmC and CcmE form a stable complex (Richard-Fogal & Kranz, 2010) as do CcmE and CcmF (San Francisco and Kranz 2014). The cytochrome c maturation system I, consisting of eight membrane/periplasmic proteins (CcmABCDEFGH), results in the attachment of heme to cysteine residues of cytochrome c proteins. Since all c-type cytochromes are periplasmic, heme is first transported to a periplasmic heme chaperone, CcmE. A large membrane complex, CcmABCD has been proposed to carry out this transport and linkage to CcmE. Li et al. 2022 described high resolution cryo-EM structures of CcmABCD in an unbound form, in complex with inhibitor AMP-PNP, and in complex with ATP and heme. The ATP-binding site in CcmA and the heme-binding site in CcmC were identified. They proposed a model of heme trafficking, heme transfer to CcmE, and ATP-dependent release of holoCcmE from CcmABCD. CcmABCD represents an ABC transporter complex using the energy of ATP hydrolysis for the transfer of heme from one binding partner (CcmC) to another (CcmE) (Li et al. 2022).

Accession Number:Q8XE58
Protein Name:CcmA
Length:207
Molecular Weight:23109.00
Species:Escherichia coli O157:H7 [83334]
Location1 / Topology2 / Orientation3: Cell inner membrane1 / Peripheral membrane protein2
Substrate ferroheme b

Cross database links:

RefSeq: NP_288781.1    NP_311117.1   
Entrez Gene ID: 916796    957178   
Pfam: PF00005   
BioCyc: ECOL83334:ECS3090-MONOMER   
KEGG: ece:Z3458    ecs:ECs3090   

Gene Ontology

GO:0030288 C:outer membrane-bounded periplasmic space
GO:0005886 C:plasma membrane
GO:0005524 F:ATP binding
GO:0015439 F:heme-transporting ATPase activity
GO:0017004 P:cytochrome complex assembly
GO:0006810 P:transport

References (2)

[1] “Genome sequence of enterohaemorrhagic Escherichia coli O157:H7.”  Perna N.T.et.al.   11206551
[2] “Complete genome sequence of enterohemorrhagic Escherichia coli O157:H7 and genomic comparison with a laboratory strain K-12.”  Hayashi T.et.al.   11258796

External Searches:

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MGMLEVRELL CERDERTLFS GLSFTLNAGE WVQITGSNGA GKTTLLRLLT GLSRPDAGEV 
61:	LWQGQPLHQV RDSYHQNLLW IGHQPGIKTR LTALENLHFY HRDGDTAQCL EALAQAGLAG 
121:	FEDIPVNQLS AGQQRRVALA RLWLTRATLW ILDEPFTAID VNGVDRLTQR MAQHTEQGGI 
181:	VILTTHQPLN VAESKIRRIS LTQTRAV