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Published on: June 20, 2018
Cloning and sequence analysis of cDNA for a human homolog of eubacterial ATP-dependent Lon proteases
Amerik AYu1, G V Petukhova, V G Grigorenko
1Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Science, Moscow.
Abstract:
Overlapping cDNA clones containing mRNA for a putative Lon protease (LonHS) were isolated from cDNA libraries prepared from human brain poly(A)+ RNA. The determined nucleotide sequence contains a 2814-bp open reading frame with two potential initiation codons (positions 62-64 and 338-340). The 5'-terminal 337-nucleotide fragment of LonHS mRNA is highly enriched with G and C nucleotides and could direct synthesis of the LonHS N-terminal domain. More likely this region promotes initiation of protein synthesis from the second AUG codon in a cap-independent manner. The amino acid sequence initiated at the second AUG codon includes 845 residues, over 30% of which are identical to those of eubacterial Lon proteases. Residues of the 'A' and 'B' motifs of NTP-binding pattern and a plausible catalytic serine residue are conserved in LonHS. Northern blot analysis revealed LonHS mRNA in lung, duodenum, liver and heart, but not in thymus cells.
Insights
Researchers identified a human Lon protease (LonHS) with significant similarity to bacterial proteases. This discovery sheds light on cellular protein degradation pathways and potential therapeutic targets.
Area of Science:
- Molecular Biology
- Proteomics
Background:
- The Lon protease is a crucial ATP-dependent serine protease involved in protein degradation.
- Understanding human Lon protease homologs is essential for elucidating cellular homeostasis and disease mechanisms.
Purpose of the Study:
- To isolate and characterize the human homolog of the Lon protease (LonHS).
- To investigate the structural and functional properties of the identified human Lon protease.
Main Methods:
- cDNA library screening using human brain poly(A)+ RNA.
- Nucleotide sequencing and open reading frame analysis.
- Northern blot analysis for mRNA expression profiling.
Main Results:
- Isolation of overlapping cDNA clones encoding a putative human Lon protease (LonHS).
- Identification of a 2814-bp open reading frame with two potential initiation codons.
- The deduced amino acid sequence (845 residues) shows over 30% identity to eubacterial Lon proteases, with conserved NTP-binding and catalytic motifs.
- LonHS mRNA expression was detected in lung, duodenum, liver, and heart tissues, but not in thymus.
Conclusions:
- LonHS represents a human homolog of the bacterial Lon protease.
- The conserved domains suggest a similar function in ATP-dependent proteolysis.
- Tissue-specific expression indicates a role in various physiological processes.
