Abstract
We constructed a gene encoding rCAS, recombinant constant and subrepeat protein, modeled after tandem repeats found in the major silk proteins synthesized by aquatic larvae of the midge, Chironomus tentans. Bacterially synthesized rCAS was purified to near homogeneity and characterized by several biochemical and biophysical methods including amino-terminal sequencing, amino acid compositional analysis, sedimentation equilibrium ultracentrifugation, and mass spectrometry. Complementing these techniques with quantitative sulfhydryl assays, we discovered that the four cysteines present in rCAS form two intramolecular disulfide bonds. Mapping studies revealed that the disulfide bonds are heterogeneous. When reduced and denatured rCAS was allowed to refold and its disulfide bonding state monitored, it again adopted a conformation with two intramolecular disulfide bonds. The inherent ability of rCAS to quantitatively form two intramolecular disulfide bonds may reflect a previously unknown feature of the in vivo silk proteins from which it is derived.
Full Text
The Full Text of this article is available as a PDF (2.2 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Case S. T., Byers M. R. Repeated nucleotide sequence arrays in Balbiani ring 1 of Chironomus tentans contain internally nonrepeating and subrepeating elements. J Biol Chem. 1983 Jun 25;258(12):7793–7799. [PubMed] [Google Scholar]
- Dillon P. J., Rosen C. A. A rapid method for the construction of synthetic genes using the polymerase chain reaction. Biotechniques. 1990 Sep;9(3):298–300. [PubMed] [Google Scholar]
- ELLMAN G. L. Tissue sulfhydryl groups. Arch Biochem Biophys. 1959 May;82(1):70–77. doi: 10.1016/0003-9861(59)90090-6. [DOI] [PubMed] [Google Scholar]
- Edmonds C. G., Smith R. D. Electrospray ionization mass spectrometry. Methods Enzymol. 1990;193:412–431. doi: 10.1016/0076-6879(90)93430-s. [DOI] [PubMed] [Google Scholar]
- Galler R., Rydlander L., Riedel N., Kluding H., Edström J. E. Balbiani ring induction in phosphate metabolism. Proc Natl Acad Sci U S A. 1984 Mar;81(5):1448–1452. doi: 10.1073/pnas.81.5.1448. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hamodrakas S. J., Kafatos F. C. Structural implications of primary sequences from a family of Balbiani ring-encoded proteins in Chironomus. J Mol Evol. 1984;20(3-4):296–303. doi: 10.1007/BF02104735. [DOI] [PubMed] [Google Scholar]
- Hillenkamp F., Karas M. Mass spectrometry of peptides and proteins by matrix-assisted ultraviolet laser desorption/ionization. Methods Enzymol. 1990;193:280–295. doi: 10.1016/0076-6879(90)93420-p. [DOI] [PubMed] [Google Scholar]
- Hunkapiller M. W., Hewick R. M., Dreyer W. J., Hood L. E. High-sensitivity sequencing with a gas-phase sequenator. Methods Enzymol. 1983;91:399–413. doi: 10.1016/s0076-6879(83)91038-8. [DOI] [PubMed] [Google Scholar]
- Hwang C., Sinskey A. J., Lodish H. F. Oxidized redox state of glutathione in the endoplasmic reticulum. Science. 1992 Sep 11;257(5076):1496–1502. doi: 10.1126/science.1523409. [DOI] [PubMed] [Google Scholar]
- Johnson M. L., Correia J. J., Yphantis D. A., Halvorson H. R. Analysis of data from the analytical ultracentrifuge by nonlinear least-squares techniques. Biophys J. 1981 Dec;36(3):575–588. doi: 10.1016/S0006-3495(81)84753-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kao W. Y., Case S. T. A novel giant secretion polypeptide in Chironomus salivary glands: implications for another Balbiani ring gene. J Cell Biol. 1985 Sep;101(3):1044–1051. doi: 10.1083/jcb.101.3.1044. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
- Lendahl U., Wieslander L. Balbiani ring 6 gene in Chironomus tentans: a diverged member of the Balbiani ring gene family. Cell. 1984 Apr;36(4):1027–1034. doi: 10.1016/0092-8674(84)90052-7. [DOI] [PubMed] [Google Scholar]
- Mullis K. B., Faloona F. A. Specific synthesis of DNA in vitro via a polymerase-catalyzed chain reaction. Methods Enzymol. 1987;155:335–350. doi: 10.1016/0076-6879(87)55023-6. [DOI] [PubMed] [Google Scholar]
- Penefsky H. S. Reversible binding of Pi by beef heart mitochondrial adenosine triphosphatase. J Biol Chem. 1977 May 10;252(9):2891–2899. [PubMed] [Google Scholar]
- Rothwarf D. M., Scheraga H. A. Regeneration of bovine pancreatic ribonuclease A. 1. Steady-state distribution. Biochemistry. 1993 Mar 16;32(10):2671–2679. doi: 10.1021/bi00061a027. [DOI] [PubMed] [Google Scholar]
- Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Snyder G. H., Cennerazzo M. J., Karalis A. J., Field D. Electrostatic influence of local cysteine environments on disulfide exchange kinetics. Biochemistry. 1981 Nov 10;20(23):6509–6519. doi: 10.1021/bi00526a001. [DOI] [PubMed] [Google Scholar]
- Wada K., Aota S., Tsuchiya R., Ishibashi F., Gojobori T., Ikemura T. Codon usage tabulated from the GenBank genetic sequence data. Nucleic Acids Res. 1990 Apr 25;18 (Suppl):2367–2411. doi: 10.1093/nar/18.suppl.2367. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wellman S. E., Case S. T. Disassembly and reassembly in vitro of complexes of secretory proteins from Chironomus tentans salivary glands. J Biol Chem. 1989 Jun 25;264(18):10878–10883. [PubMed] [Google Scholar]
- Wellman S. E., Hamodrakas S. J., Kamitsos E. I., Case S. T. Secondary structure of synthetic peptides derived from the repeating unit of a giant secretory protein from Chironomus tentans. Biochim Biophys Acta. 1992 Jun 24;1121(3):279–285. doi: 10.1016/0167-4838(92)90157-9. [DOI] [PubMed] [Google Scholar]
- Wieslander L., Hög C., Hög J. O., Jörnvall H., Lendahl U., Daneholt B. Conserved and nonconserved structures in the secretory proteins encoded in the Balbiani ring genes of Chironomus tentans. J Mol Evol. 1984;20(3-4):304–312. doi: 10.1007/BF02104736. [DOI] [PubMed] [Google Scholar]
- Wieslander L. The Balbiani ring multigene family: coding repetitive sequences and evolution of a tissue-specific cell function. Prog Nucleic Acid Res Mol Biol. 1994;48:275–313. doi: 10.1016/s0079-6603(08)60858-2. [DOI] [PubMed] [Google Scholar]