Isolation and sequence of omcA, a gene encoding a decaheme outer membrane cytochrome c of Shewanella putrefaciens MR-1, and detection of omcA homologs in other strains of S. putrefaciens

AbstractThe sequence of the omcA gene, which encodes a decaheme cytochrome c that is localized to the outer membrane (OM) of Shewanella putrefaciens MR-1, was determined. The 2202 bp nucleotide sequence of omcA encodes for 734 amino acids with a predicted molecular protein mass of 78.6 kDa. Comparison with the amino-terminal sequence of the mature protein suggests the presence of a hydrophobic leader sequence which is cleaved during translocation of the protein to the OM. This leader sequence has a lipoprotein consensus sequence for signal peptidase II at the cleavage site. The predicted mature protein is comprised of 708 amino acids with a predicted molecular mass of 75.8 kDa, but the addition of ten covalently attached heme c groups and covalent lipid modification to the amino-terminal cysteine increases the predicted mass to 82.7 kDa. This is consistent with its apparent mass of 83 kDa in SDS-PAGE gels. The predicted amino acid sequence for the OmcA protein shows no significant homology to known proteins. A RNA of approx. 2300 bases that hybridizes to the omcA gene was detected in anaerobically grown MR-1 cells. The size of this transcript is similar to the coding region of the omcA gene, suggesting that it is not part of a multicistronic operon. Similar to MR-1, four other strains of S. putrefaciens were all found to localize a majority of their membrane-bound cytochromes to the OM when grown under anaerobic conditions, and all contained an OM cytochrome of similar size to OmcA. In two of these strains, MR-4 and MR-8, a homolog of omcA was identified by RT-PCR and Southern blotting using primers and probes specific for omcA of MR-1. Western blot analysis using a polyclonal antibody to OmcA was similarly positive in strains MR-4 and MR-8. Partial nucleotide sequence analysis of these homologs demonstrated 74–77% predicted amino acid homology with OmcA of MR-1. In contrast, strains MR-30 and MR-42 tested negative for omcA homologs by Southern and Northern blots, RT-PCR, and Western blots

Elements of Change

Historically there have been many models of change introduced to attempt to improve student achievement. The purpose of this paper was to explore some of the elements of the change process. The researcher conducted a literature review of several of the leading theorists whose research suggests different factors contribute to the success or failure of adopting change. The research suggests the success or failure of adopting change starts with the leader. The research could assist other scholars to understand the many elements of the change process and the possibility of using a combination of those elements for successful implementation of change

An Interactive, graphical typeface identification system

Most, if not all, published type identification books suffer from serious drawbacks which make them difficult to use by both typographic novices and professionals. Few effective computerized programs exist to simplify the identification of typefaces. The purpose of this project is to create an effective, visually attractive, interactive and easy-to-use model of a type identification system, which, if successful, will be fully developed. This is accomplished by combining the graphics and interactivity of the World Wide Web with the database management capabilities of modern database products. The user is given a series of questions regarding readily observable structural characteristics of the unknown typeface, such as whether the bar of the e slopes or is horizontal. The identification is based on the user\u27s answers. By using the World Wide Web, the prototype typeface identification system can be provided as a service to the design and desktop publishing community, relieving users from hours of frustration manually searching typeface identification books