title: Antimicrobial activity of histones from hemocytes of the Pacific white shrimp.
abstract: The role of vertebrate histone proteins or histone derived peptides as innate immune effectors has only recently been appreciated. In this study, high levels of core histone proteins H2A, H2B, H3 and H4 were found in hemocytes from the Pacific white shrimp, Litopenaeus vannamei. The proteins were identified by in-gel digestion, mass spectrometry analysis, and homology searching. The L. vannamei histone proteins were found to be highly homologous to histones of other species. Based on this homology, histone H2A was cloned and its N-terminus was found to resemble the known antimicrobial histone peptides buforin I, parasin, and hipposin. Consequently, a 38 amino acid synthetic peptide identical to the N-terminus of shrimp H2A was synthesized and assayed, along with endogenous histones H2A, H2B, and H4, for growth inhibition against Micrococcus luteus. Histone H2A, purified to homogeneity, completely inhibited growth of the Gram-positive bacterium at 4.5 microm while a mixture of histones H2B and H4 was active at 3 microm. In addition, a fraction containing a fragment of histone H1 was also found to be active. The synthetic peptide similar to buforin was active at submicromolar concentrations. These data indicate, for the first time, that shrimp hemocyte histone proteins possess antimicrobial activity and represent a defense mechanism previously unreported in an invertebrate. Histones may be a component of innate immunity more widely conserved, and of earlier origin, than previously thought.
authors.affiliation: Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: Séverine A
authors.initials: SA
authors.lastname: Patat
authors.forename: Ryan B
authors.initials: RB
authors.lastname: Carnegie
authors.forename: Celia
authors.initials: C
authors.lastname: Kingsbury
authors.forename: Paul S
authors.initials: PS
authors.lastname: Gross
authors.forename: Robert
authors.initials: R
authors.lastname: Chapman
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Schey
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001483:Base Sequence; D003001:Cloning, Molecular; D003445:Crustacea / Q000737:chemistry*; D017931:DNA Primers; D018076:DNA, Complementary; D006434:Hemocytes / Q000737:chemistry*; D006657:Histones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000890:Anti-Infective Agents; D017931:DNA Primers; D018076:DNA, Complementary; D006657:Histones