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Lon peptidase 1, mitochondrial
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols LONP1 ; LON; LONP; LonHS; PIM1; PRSS15; hLON
External IDs OMIM605490 MGI1921392 HomoloGene3521 GeneCards: LONP1 Gene
RNA expression pattern
PBB GE LONP1 209017 s at tn.png
More reference expression data
Species Human Mouse
Entrez 9361 74142
Ensembl ENSG00000196365 ENSMUSG00000041168
UniProt P36776 Q8CGK3
RefSeq (mRNA) NM_001276479 NM_028782
RefSeq (protein) NP_001263408 NP_083058
Location (UCSC) Chr 19:
5.69 – 5.72 Mb
Chr 17:
56.61 – 56.63 Mb
PubMed search [1] [2]

Lon protease homolog, mitochondrial is an enzyme that in humans is encoded by the LONP1 gene.[1][2][3]

This gene encoded a mitochondrial matrix protein that is the subunit of a barrel-shaped homo-oligometric protein complex, the Lon protease. Lon protease is a member of ATP-dependent proteases (AAA+ proteases). Mature and catalytically viable Human Lon protease complex contains a hexameric ring while other formations of complexes have been observed (e.g., heptameric ring in Saccharomyces cerevisiae). A single subunit of Lon protease contains three domains, N-Domain for protein substrate recognition, AAA + module for ATP binding and hydrolysis, and P-domain for protein proteolysis. A similar protease expressed in E. coli regulates gene expression by targeting specific regulatory proteins for degradation. Lon protease binds a specific sequence in the light and heavy chain promoters of the mitochondrial genome which are involved in regulation of DNA replication and transcription.[3]


Lon protease (LONP1) is a conserved serine peptidase identified from bacteria to eukaryotic cells.[4] In mitochondrial matrix, a majority of damaged proteins is removed via proteolysis led by Lon protease, which is an essential mechanism for mitochondrial protein quality control (PQC). For Lon protease-dependent degradation, protein substrates are first recognized and then unfolded if necessary in an ATP-dependent manner. The substrates are subsequently transferred through the pore of complex and into the proteolytic chamber of complex for degradation. ATP binding to the AAA module of the Lon complex results in a change in Lon conformation into a proteolytically active state. In general, Lon protease interacts with peptide regions(sequences) that are located within the hydrophobic core of substrates and rarely on the surface. These regions can be presented to Lon protease when proteins are damaged and lost their conformation integrity.[5] In addition to misfolded proteins, several regulatory proteins can be processed by Lon protease by removing a degradable tag before they fully gain their biological functions.[6] LONP1 is also a DNA-binding protein that participates in mtDNA maintenance and gene expression regulation.[7] LONP1 degrades mitochondrial transcription factor A (TFAM) when substrate is modified by post-translational modifications (PTMs) such as phosphorylation, regulating mtDNA copy number and metabolism to maintain the TFAM/mtDNA ratio necessary to control replication and transcription.[8]

Clinical Significance[edit]

Given the crucial role of LON protease in maintaining the control of mitochondrial function, its dynamics in expression under stress conditions has been found associating with human diseases and aging.[9][10] For example, LONP1 expression levels are increased in different tumors and tumor cell lines. Interestingly, downregulation of LONP1 in some tumor cells causes apoptosis and cell death, indicating a possible addiction of tumor cells to LONP1 function, as occurs with other intracellular proteases associated with cancer.


  1. ^ Wang N, Gottesman S, Willingham MC, Gottesman MM, Maurizi MR (Jan 1994). "A human mitochondrial ATP-dependent protease that is highly homologous to bacterial Lon protease". Proc Natl Acad Sci U S A 90 (23): 11247–51. doi:10.1073/pnas.90.23.11247. PMC 47959. PMID 8248235. 
  2. ^ Amerik AYu, Petukhova GV, Grigorenko VG, Lykov IP, Yarovoi SV, Lipkin VM, Gorbalenya AE (Apr 1994). "Cloning and sequence analysis of cDNA for a human homolog of eubacterial ATP-dependent Lon proteases". FEBS Lett 340 (1–2): 25–8. doi:10.1016/0014-5793(94)80166-5. PMID 8119403. 
  3. ^ a b "Entrez Gene: LONP1 lon peptidase 1, mitochondrial". 
  4. ^ Lu, B; Liu, T; Crosby, JA; Thomas-Wohlever, J; Lee, I; Suzuki, CK (13 March 2003). "The ATP-dependent Lon protease of Mus musculus is a DNA-binding protein that is functionally conserved between yeast and mammals.". Gene 306: 45–55. PMID 12657466. 
  5. ^ Gur, E; Sauer, RT (15 August 2008). "Recognition of misfolded proteins by Lon, a AAA(+) protease.". Genes & development 22 (16): 2267–77. PMID 18708584. 
  6. ^ Birghan, C; Mundt, E; Gorbalenya, AE (4 January 2000). "A non-canonical lon proteinase lacking the ATPase domain employs the ser-Lys catalytic dyad to exercise broad control over the life cycle of a double-stranded RNA virus.". The EMBO journal 19 (1): 114–23. PMID 10619850. 
  7. ^ Liu, T; Lu, B; Lee, I; Ondrovicová, G; Kutejová, E; Suzuki, CK (2 April 2004). "DNA and RNA binding by the mitochondrial lon protease is regulated by nucleotide and protein substrate.". The Journal of biological chemistry 279 (14): 13902–10. PMID 14739292. 
  8. ^ Lu, B; Lee, J; Nie, X; Li, M; Morozov, YI; Venkatesh, S; Bogenhagen, DF; Temiakov, D; Suzuki, CK (10 January 2013). "Phosphorylation of human TFAM in mitochondria impairs DNA binding and promotes degradation by the AAA+ Lon protease.". Molecular cell 49 (1): 121–32. PMID 23201127. 
  9. ^ Ngo, JK; Pomatto, LC; Davies, KJ (9 February 2013). "Upregulation of the mitochondrial Lon Protease allows adaptation to acute oxidative stress but dysregulation is associated with chronic stress, disease, and aging.". Redox biology 1: 258–64. PMID 24024159. 
  10. ^ Hamon, MP; Bulteau, AL; Friguet, B (8 January 2015). "Mitochondrial proteases and protein quality control in ageing and longevity.". Ageing research reviews. PMID 25578288. 

Further reading[edit]