Cloning and characterization of an actin-resistant DNase I-like endonuclease secreted by macrophages
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Published on: November 3, 2014
W F Baron1, C Q Pan, S A Spencer
1Department of Molecular Biology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA. baker.kevin@gene.com
Abstract:
We have cloned human and murine DNase I-like cDNAs, termed LS-DNase, which are expressed at high levels in liver and spleen tissues. LS-DNase expression is highly specific to macrophage populations within these and other tissues. Mature LS-DNase from both species is a secreted, non-glycosylated protein containing 285 residues, with a calculated molecular mass of 33 kDa and a basic isoelectric point. Human and murine LS-DNase are highly conserved and share 83% identity. Sequence analysis reveals that LS-DNase shares 46% amino acid sequence identity with DNase I. However, several residues identified as important for interaction of human DNase I with actin are not conserved in both human and murine LS-DNase. Consistent with this observation, recombinant human LS-DNase possesses a DNA hydrolytic activity which, unlike DNase I, is not inhibited by G-actin. The existence of a family of DNase I-like molecules that have tissue-specific expression patterns and the possible role of a macrophage specific DNase are discussed.
Insights
Researchers identified LS-DNase, a novel DNA-hydrolyzing enzyme highly expressed in liver and spleen macrophages. Unlike DNase I, LS-DNase activity is not inhibited by G-actin, suggesting unique biological functions.
Area of Science:
- Molecular Biology
- Biochemistry
- Immunology
Background:
- DNase I is an enzyme that degrades DNA.
- The existence of DNase I-like molecules with distinct functions is largely unexplored.
- Understanding novel DNase enzymes is crucial for cellular processes.
Purpose of the Study:
- To clone and characterize novel DNase I-like cDNAs, termed LS-DNase.
- To investigate the expression patterns and biochemical properties of LS-DNase.
- To compare LS-DNase with DNase I and explore its unique characteristics.
Main Methods:
- Cloning of human and murine LS-DNase cDNAs.
- Analysis of LS-DNase expression in various tissues and cell populations.
- Biochemical characterization of recombinant human LS-DNase, including DNA hydrolytic activity assays.
- Sequence analysis and comparison with DNase I.
Main Results:
- LS-DNase cDNAs were successfully cloned from human and murine sources.
- LS-DNase is highly expressed in liver and spleen, specifically in macrophage populations.
- Mature LS-DNase is a secreted, non-glycosylated protein with high conservation between species.
- LS-DNase shares 46% identity with DNase I but lacks G-actin inhibition of its DNA hydrolytic activity.
Conclusions:
- LS-DNase represents a novel DNase I-like enzyme with tissue-specific expression, particularly in macrophages.
- The unique biochemical property of LS-DNase, its resistance to G-actin inhibition, suggests distinct biological roles compared to DNase I.
- Further research into LS-DNase function may reveal its significance in macrophage biology and other cellular processes.
