CC0572 has some sequence similarity to chitinases, suggesting that it might be involved in exopolysaccharide metabolism. Consistent with this hypothesis, cells lacking CC0572 could not be infected with phage WCr30, which uses the S-layer protein attached to the exopolysaccharide as a receptor. To determine if CC0572 was required for normal cell structure, a deletion of the CC0572 gene was engineered and cell beta-Eudesmol growth and morphology were assessed under a variety of nutrient and growth conditions. No defects were seen for these cells during lag phase, exponential growth, or stationary phase in complex medium or defined media. Likewise, no defects in colony morphology were seen for growth on solid media. These results indicate that although CC0572 is produced and localized during exponential growth in culture, it is not required for most processes under laboratory conditions. CC0572 may play an auxiliary role or provide a redundant enzymatic activity, so that absence of CC0572 is not deleterious. Alternatively, CC0572 may be necessary only under particular growth conditions that were not assayed here. The Resibufogenin transposon-based strategy employed here successfully identified localized proteins in C. crescentus, and could be adapted for any species that is compatible with transposon mutagenesis. The first sequencing efforts identified eleven previously unknown localized proteins out of 24 clones that were sequenced. Because over 1000 clones with localized GFP signal were obtained, there are likely to be many more localized proteins in C. crescentus than have been described to date. This point is accentuated by two groups of localized proteins, those involved in processes for which there is no obvious requirement for localized function, such as metabolism and stress response, and hypothetical proteins. SerA and alanine dehydrogenase are each localized, even though the substrates and products of amino acid metabolism can presumably diffuse rapidly throughout the cell. SerA is also localized in E. coli, so it is unlikely that this phenomenon is peculiar to C. crescentus. One possible rationale for localizing biosynthetic enzymes is to limit diffusion of unstable or harmful reaction intermediates. Six of the localized proteins were annotated as hypothetical, a category that comprises 37% of the C. crescentus proteome.