Characterization and expression of HLysG2, a basic goose-type lysozyme from the human eye and testis

Mol Immunol. 2011 Jan;48(4):524-31. doi: 10.1016/j.molimm.2010.10.008. Epub 2010 Nov 18.


Lysozyme plays an important role in human innate immunity by causing bacterial cell lysis. We describe for the first time, the actual performance of human lysozyme g-like 2 (HLysG2), a mammalian g-type lysozyme. RT-PCR revealed that the HLysG2 gene was transcribed in eye and testis tissues. A spot was detected from human tears using 2D gel electrophoresis and was identified as HLysG2 using MALDI-TOF/TOF MS and a MASCOT search with a matching score of 140 and 27% sequence coverage of the whole amino acid sequence. To gain insight into the in vitro antimicrobial activities of HLysG2, the mature peptide-coding region was cloned into Pichia pastoris for heterogeneous expression. Recombinant HLysG2, had an optimal at pH 6.0 and 30 °C, reached the peak activity of 1.2 × 10(4)U/mg at the sodium ion concentration of 75 mM and showed a higher salt tolerance than human c-type lysozyme (HLysC). Recombinant HlysG2 inhibited Gram-positive bacterial growth and did not inhibit Gram-negative bacterial and Candida albicans growth. Results indicated that HLysG2 is a potent antibacterial protein that may play a role in the innate immunity of the human eye.

MeSH terms

  • Amino Acid Sequence
  • Anti-Infective Agents / pharmacology
  • Bacteria / drug effects
  • Bacteria / growth & development
  • Electrophoresis, Polyacrylamide Gel
  • Eye / enzymology*
  • Gene Expression Profiling
  • Gene Expression Regulation, Enzymologic / drug effects
  • Humans
  • Hydrogen-Ion Concentration / drug effects
  • Male
  • Microbial Sensitivity Tests
  • Molecular Sequence Data
  • Muramidase / chemistry
  • Muramidase / genetics
  • Muramidase / isolation & purification
  • Muramidase / metabolism*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Tears / drug effects
  • Tears / enzymology
  • Temperature
  • Testis / enzymology*


  • Anti-Infective Agents
  • Recombinant Proteins
  • Muramidase