Skip to main content
PMC home page
Journal of Bacteriology logoLink to Journal of Bacteriology
. 1997 Sep;179(18):5928–5934. doi: 10.1128/jb.179.18.5928-5934.1997

The chlamydial EUO gene encodes a histone H1-specific protease.

R Kaul 1, A Hoang 1, P Yau 1, E M Bradbury 1, W M Wenman 1
PMCID: PMC179486  PMID: 9294454

Abstract

Chlamydia trachomatis is an obligate intracellular pathogen, long recognized as an agent of blinding eye disease and more recently as a common sexually transmitted infection. Recently, two eukaryotic histone H1-like proteins, designated Hc1 and Hc2, have been identified in Chlamydia. Expression of Hc1 in recombinant Escherichia coli produces chromatin condensation similar to nucleoid condensation observed late in the parasite's own life cycle. In contrast, chromatin decondensation, observed during the early life cycle, accompanies down-regulation and nondetection of Hc1 and Hc2 among internalized organisms. We reasoned that the early upstream open reading frame (EUO) gene product might play a role in Hc1 degradation and nucleoid decondensation since it is expressed very early in the chlamydial life cycle. To explore this possibility, we fused the EUO coding region between amino acids 4 and 177 from C. trachomatis serovar Lz with glutathione S-transferase (GST) and examined the effects of fusion protein on Hc1 in vitro. The purified fusion protein was able to digest Hc1 completely within 1 h at 37 degrees C. However, GST alone exhibited no Hc1-specific proteolytic activity. The chlamydial EUO-GST gene product also cleaves very-lysine-rich calf thymus histone H1 and chicken erythrocyte histone H5 but displays no measurable activity towards core histones H2A, H2B, H3, and H4 or chlamydial RNA polymerase alpha-subunit. This proteolytic activity appears sensitive to the serine protease inhibitor 4-(2-aminoethyl)-benzenesulfonyl fluoride hydrochloride (AEBSF) and aspartic protease inhibitor pepstatin but resistant to high temperature and other broad-spectrum protease inhibitors. The proteolytic activity specified by the EUO-GST fusion product selectively digested the C-terminal portion of chlamydial Hc1, the domain involved in DNA binding, while leaving the N terminus intact. At a molar equivalent ratio of 1:1 between Hc1 and DNA, the EUO gene product cleaves Hc1 complexed to DNA and this cleavage appears sufficient to initiate dissociation of DNA-Hc1 complexes. However, at a higher molar equivalent ratio of Hc1/DNA (10:1), there is partial protection conferred upon Hc1 to an extent that prevents dissociation of DNA-Hc1 complexes.

Full Text

The Full Text of this article is available as a PDF (2.3 MB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Allan J., Cowling G. J., Harborne N., Cattini P., Craigie R., Gould H. Regulation of the higher-order structure of chromatin by histones H1 and H5. J Cell Biol. 1981 Aug;90(2):279–288. doi: 10.1083/jcb.90.2.279. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Barry C. E., 3rd, Brickman T. J., Hackstadt T. Hc1-mediated effects on DNA structure: a potential regulator of chlamydial development. Mol Microbiol. 1993 Jul;9(2):273–283. doi: 10.1111/j.1365-2958.1993.tb01689.x. [DOI] [PubMed] [Google Scholar]
  3. Barry C. E., 3rd, Hayes S. F., Hackstadt T. Nucleoid condensation in Escherichia coli that express a chlamydial histone homolog. Science. 1992 Apr 17;256(5055):377–379. doi: 10.1126/science.256.5055.377. [DOI] [PubMed] [Google Scholar]
  4. Brickman T. J., Barry C. E., 3rd, Hackstadt T. Molecular cloning and expression of hctB encoding a strain-variant chlamydial histone-like protein with DNA-binding activity. J Bacteriol. 1993 Jul;175(14):4274–4281. doi: 10.1128/jb.175.14.4274-4281.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Carrillo-Martinez Y., Setlow P. Properties of Bacillus subtilis small, acid-soluble spore proteins with changes in the sequence recognized by their specific protease. J Bacteriol. 1994 Sep;176(17):5357–5363. doi: 10.1128/jb.176.17.5357-5363.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Christiansen G., Pedersen L. B., Koehler J. E., Lundemose A. G., Birkelund S. Interaction between the Chlamydia trachomatis histone H1-like protein (Hc1) and DNA. J Bacteriol. 1993 Mar;175(6):1785–1795. doi: 10.1128/jb.175.6.1785-1795.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Costerton J. W., Poffenroth L., Wilt J. C., Kordová N. Ultrastructural studies of the nucleoids of the pleomorphic forms of Chlamydia psittaci 6BC: a comparison with bacteria. Can J Microbiol. 1976 Jan;22(1):16–28. doi: 10.1139/m76-003. [DOI] [PubMed] [Google Scholar]
  8. Friis R. R. Interaction of L cells and Chlamydia psittaci: entry of the parasite and host responses to its development. J Bacteriol. 1972 May;110(2):706–721. doi: 10.1128/jb.110.2.706-721.1972. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Gu L., Wenman W. M., Remacha M., Meuser R., Coffin J., Kaul R. Chlamydia trachomatis RNA polymerase alpha subunit: sequence and structural analysis. J Bacteriol. 1995 May;177(9):2594–2601. doi: 10.1128/jb.177.9.2594-2601.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Hackstadt T., Baehr W., Ying Y. Chlamydia trachomatis developmentally regulated protein is homologous to eukaryotic histone H1. Proc Natl Acad Sci U S A. 1991 May 1;88(9):3937–3941. doi: 10.1073/pnas.88.9.3937. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Hackstadt T., Brickman T. J., Barry C. E., 3rd, Sager J. Diversity in the Chlamydia trachomatis histone homologue Hc2. Gene. 1993 Sep 30;132(1):137–141. doi: 10.1016/0378-1119(93)90526-9. [DOI] [PubMed] [Google Scholar]
  12. Hatch T. P., Allan I., Pearce J. H. Structural and polypeptide differences between envelopes of infective and reproductive life cycle forms of Chlamydia spp. J Bacteriol. 1984 Jan;157(1):13–20. doi: 10.1128/jb.157.1.13-20.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hunter A. J., Cary P. D. Preparation of chromosomal protein A24 (uH2A) by denaturing gel filtration and preparation of its free nonhistone component ubiquitin by ion-exchange chromatography. Anal Biochem. 1985 Nov 1;150(2):394–402. doi: 10.1016/0003-2697(85)90527-5. [DOI] [PubMed] [Google Scholar]
  14. Kaul R., Allen M., Bradbury E. M., Wenman W. M. Sequence specific binding of chlamydial histone H1-like protein. Nucleic Acids Res. 1996 Aug 1;24(15):2981–2989. doi: 10.1093/nar/24.15.2981. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Kaul R., Tao S., Wenman W. M. Interspecies structural diversity among chlamydial genes encoding histone H1. Gene. 1992 Mar 1;112(1):129–132. doi: 10.1016/0378-1119(92)90314-f. [DOI] [PubMed] [Google Scholar]
  16. Pedersen L. B., Birkelund S., Christiansen G. Interaction of the Chlamydia trachomatis histone H1-like protein (Hc1) with DNA and RNA causes repression of transcription and translation in vitro. Mol Microbiol. 1994 Mar;11(6):1085–1098. doi: 10.1111/j.1365-2958.1994.tb00385.x. [DOI] [PubMed] [Google Scholar]
  17. Pedersen L. B., Birkelund S., Holm A., Ostergaard S., Christiansen G. The 18-kilodalton Chlamydia trachomatis histone H1-like protein (Hc1) contains a potential N-terminal dimerization site and a C-terminal nucleic acid-binding domain. J Bacteriol. 1996 Feb;178(4):994–1002. doi: 10.1128/jb.178.4.994-1002.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Perara E., Ganem D., Engel J. N. A developmentally regulated chlamydial gene with apparent homology to eukaryotic histone H1. Proc Natl Acad Sci U S A. 1992 Mar 15;89(6):2125–2129. doi: 10.1073/pnas.89.6.2125. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Remacha M., Kaul R., Sherburne R., Wenman W. M. Functional domains of chlamydial histone H1-like protein. Biochem J. 1996 Apr 15;315(Pt 2):481–486. doi: 10.1042/bj3150481. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Smith D. B., Johnson K. S. Single-step purification of polypeptides expressed in Escherichia coli as fusions with glutathione S-transferase. Gene. 1988 Jul 15;67(1):31–40. doi: 10.1016/0378-1119(88)90005-4. [DOI] [PubMed] [Google Scholar]
  21. Studier F. W., Rosenberg A. H., Dunn J. J., Dubendorff J. W. Use of T7 RNA polymerase to direct expression of cloned genes. Methods Enzymol. 1990;185:60–89. doi: 10.1016/0076-6879(90)85008-c. [DOI] [PubMed] [Google Scholar]
  22. Takashima K., Kawashima S., Imahori K. Reconstitution of compact polynucleosomes and comparison of the functions of histones H1 and H5. J Biochem. 1984 Oct;96(4):1071–1078. doi: 10.1093/oxfordjournals.jbchem.a134924. [DOI] [PubMed] [Google Scholar]
  23. Tao S., Kaul R., Wenman W. M. Identification and nucleotide sequence of a developmentally regulated gene encoding a eukaryotic histone H1-like protein from Chlamydia trachomatis. J Bacteriol. 1991 May;173(9):2818–2822. doi: 10.1128/jb.173.9.2818-2822.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Wenman W. M., Meuser R. U. Chlamydia trachomatis elementary bodies possess proteins which bind to eucaryotic cell membranes. J Bacteriol. 1986 Feb;165(2):602–607. doi: 10.1128/jb.165.2.602-607.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Wichlan D. G., Hatch T. P. Identification of an early-stage gene of Chlamydia psittaci 6BC. J Bacteriol. 1993 May;175(10):2936–2942. doi: 10.1128/jb.175.10.2936-2942.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES