PMPCB

Mitochondrial-processing peptidase subunit beta is an enzyme that in humans is encoded by the PMPCB gene.^[5][6] This gene is a member of the peptidase M16 family and encodes a protein with a zinc-binding motif. This protein is located in the mitochondrial matrix and catalyzes the cleavage of the leader peptides of precursor proteins newly imported into the mitochondria, though it only functions as part of a heterodimeric complex.^[6]

PMPCB
Identifiers
Aliases	PMPCB, Beta-MPP, MPP11, MPPB, MPPP52, P-52, peptidase, mitochondrial processing beta subunit, peptidase, mitochondrial processing subunit beta, MAS1
External IDs	OMIM: 603131; MGI: 1920328; HomoloGene: 3160; GeneCards: PMPCB; OMA:PMPCB - orthologs
Gene location (Human) Chr. Chromosome 7 (human)[1] Band 7q22.1 Start 103,297,435 bp[1] End 103,329,511 bp[1]
Gene location (Mouse) Chr. Chromosome 5 (mouse)[2] Band 5|5 A3 Start 21,942,139 bp[2] End 21,962,150 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in right adrenal cortex parotid gland left adrenal gland body of pancreas left adrenal cortex skin of thigh gastric mucosa skin of hip rectum left ovary Top expressed in spermatid spermatocyte medullary collecting duct renal corpuscle cardiac muscle tissue of left ventricle endocardial cushion atrioventricular valve right kidney proximal tubule interventricular septum More reference expression data BioGPS More reference expression data
Gene ontology Molecular function zinc ion binding peptidase activity catalytic activity hydrolase activity metallopeptidase activity metal ion binding metalloendopeptidase activity endopeptidase activity Cellular component mitochondrial respiratory chain complex III mitochondrial matrix mitochondrion mitochondrial inner membrane mitochondrial processing peptidase complex Biological process mitochondrial electron transport, ubiquinol to cytochrome c aerobic respiration protein processing proteolysis mitochondrial calcium ion transmembrane transport protein processing involved in protein targeting to mitochondrion Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 9512 73078 Ensembl ENSG00000105819 ENSMUSG00000029017 UniProt O75439 Q9CXT8 RefSeq (mRNA) NM_004279 NM_028431 RefSeq (protein) NP_004270 NP_082707 Location (UCSC) Chr 7: 103.3 – 103.33 Mb Chr 5: 21.94 – 21.96 Mb PubMed search [3] [4]
Wikidata
View/Edit Human View/Edit Mouse

Structure

The Mitochondrial-processing peptidase subunit beta precursor protein is 54.4 KDa in size and composed of 489 amino acids. The precursor protein contains a 45 amino acid N-terminal fragment as mitochondrion targeting sequence. After cleavage, the matured PMPCB protein is 49.5 KDa in size and has a theoretical pI of 5.76.

Function

Mitochondrial-processing peptidase (MPP) is a metalloendopeptidase, containing two structurally related subunits, mitochondrial-processing peptidase subunit alpha and subunit beta, working in conjunction for its catalytic function.^[7] Containing the catalytic site, the beta subunit PMPCB protein cleaves presequences (transit peptides) from mitochondrial protein precursors and releases of N-terminal transit peptides from precursor proteins imported into the mitochondrion, typically with Arg in position P2.

Interactions

As the beta subunit of Mitochondrial-processing peptidase, PMPCB forms a heterodimer with the subunit Mitochondrial-processing peptidase subunit alpha. In addition, PMPCB has been shown to interact with PMPCA and Frataxin.^[8]

Clinical significance

The majority of mitochondrial proteins is nuclear-coded, which necessitates proper translocations of mitochondrial targeting proteins. Many mitochondrial proteins are synthesized in a precursor form that contains mitochondria targeting sequence. These precursors are usually cleaved by peptidases and proteases before they arrive their sub-organellar locations. It is likely that altered activity of the mitochondrial processing peptidases is essential to ensure the correct maturation of mitochondrial proteins and that altered activity of these proteases will have dramatic effects in the activity, stability and assembly of mitochondrial proteins. Evidences showed that MPP was involved in the proteolytic maturation of Frataxin, a protein responsible for iron homeostasis.^[9] Accordingly, MPP deficiency was shown to be involved in Friedreich ataxia, an autossomic recessive neurodegenerative disorder^[10][11]

References

1. GRCh38: Ensembl release 89: ENSG00000105819 – Ensembl, May 2017
2. GRCm38: Ensembl release 89: ENSMUSG00000029017 – Ensembl, May 2017
3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
5. Mao M, Fu G, Wu JS, Zhang QH, Zhou J, Kan LX, Huang QH, He KL, Gu BW, Han ZG, Shen Y, Gu J, Yu YP, Xu SH, Wang YX, Chen SJ, Chen Z (Jul 1998). "Identification of genes expressed in human CD34(+) hematopoietic stem/progenitor cells by expressed sequence tags and efficient full-length cDNA cloning". Proceedings of the National Academy of Sciences of the United States of America. 95 (14): 8175–80. Bibcode:1998PNAS...95.8175M. doi:10.1073/pnas.95.14.8175. PMC 20949. PMID 9653160.
6. "Entrez Gene: PMPCB peptidase (mitochondrial processing) beta".
7. Teixeira PF, Glaser E (Feb 2013). "Processing peptidases in mitochondria and chloroplasts". Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1833 (2): 360–70. doi:10.1016/j.bbamcr.2012.03.012. PMID 22495024.
8. Koutnikova H, Campuzano V, Koenig M (Sep 1998). "Maturation of wild-type and mutated frataxin by the mitochondrial processing peptidase". Human Molecular Genetics. 7 (9): 1485–9. doi:10.1093/hmg/7.9.1485. PMID 9700204.
9. Branda SS, Yang ZY, Chew A, Isaya G (Jun 1999). "Mitochondrial intermediate peptidase and the yeast frataxin homolog together maintain mitochondrial iron homeostasis in Saccharomyces cerevisiae". Human Molecular Genetics. 8 (6): 1099–110. doi:10.1093/hmg/8.6.1099. PMID 10332043.
10. Cavadini P, Adamec J, Taroni F, Gakh O, Isaya G (Dec 2000). "Two-step processing of human frataxin by mitochondrial processing peptidase. Precursor and intermediate forms are cleaved at different rates". The Journal of Biological Chemistry. 275 (52): 41469–75. doi:10.1074/jbc.M006539200. PMID 11020385.
11. Patel PI, Isaya G (Jul 2001). "Friedreich ataxia: from GAA triplet-repeat expansion to frataxin deficiency". American Journal of Human Genetics. 69 (1): 15–24. doi:10.1086/321283. PMC 1226030. PMID 11391483.

Further reading

• Koutnikova H, Campuzano V, Koenig M (Sep 1998). "Maturation of wild-type and mutated frataxin by the mitochondrial processing peptidase". Human Molecular Genetics. 7 (9): 1485–9. doi:10.1093/hmg/7.9.1485. PMID 9700204.
• Gordon DM, Shi Q, Dancis A, Pain D (Nov 1999). "Maturation of frataxin within mammalian and yeast mitochondria: one-step processing by matrix processing peptidase". Human Molecular Genetics. 8 (12): 2255–62. doi:10.1093/hmg/8.12.2255. PMID 10545606.
• Nagao Y, Kitada S, Kojima K, Toh H, Kuhara S, Ogishima T, Ito A (Nov 2000). "Glycine-rich region of mitochondrial processing peptidase alpha-subunit is essential for binding and cleavage of the precursor proteins". The Journal of Biological Chemistry. 275 (44): 34552–6. doi:10.1074/jbc.M003110200. PMID 10942759.
• Zhang QH, Ye M, Wu XY, Ren SX, Zhao M, Zhao CJ, Fu G, Shen Y, Fan HY, Lu G, Zhong M, Xu XR, Han ZG, Zhang JW, Tao J, Huang QH, Zhou J, Hu GX, Gu J, Chen SJ, Chen Z (Oct 2000). "Cloning and functional analysis of cDNAs with open reading frames for 300 previously undefined genes expressed in CD34+ hematopoietic stem/progenitor cells". Genome Research. 10 (10): 1546–60. doi:10.1101/gr.140200. PMC 310934. PMID 11042152.
• Schwer B, North BJ, Frye RA, Ott M, Verdin E (Aug 2002). "The human silent information regulator (Sir)2 homologue hSIRT3 is a mitochondrial nicotinamide adenine dinucleotide-dependent deacetylase". The Journal of Cell Biology. 158 (4): 647–57. doi:10.1083/jcb.200205057. PMC 2174009. PMID 12186850.
• Suzuki Y, Yamashita R, Shirota M, Sakakibara Y, Chiba J, Mizushima-Sugano J, Nakai K, Sugano S (Sep 2004). "Sequence comparison of human and mouse genes reveals a homologous block structure in the promoter regions". Genome Research. 14 (9): 1711–8. doi:10.1101/gr.2435604. PMC 515316. PMID 15342556.