Anti-KIAA1737 polyclonal antibody

Twelve genes encoding key components of Clostridium cellulolyticum cellulosomes are clustered. Among them, the first, second, and fifth genes encode the assembly factor CipC and the two major cellulases Cel48F and Cel9E, respectively. Cellulolytic clones were selected from the noncellulolytic cipC insertional mutant trans-complemented with a cipC expression vector, in which one homologous recombination event between the 3' end of the chromosomal cipC gene and the plasmidic cipC gene has restored the cluster continuity. The absence of the enzymes encoded by the cluster in the cipC mutant was thus only clue to a strong polar effect, indicating that all genes were transcriptionally linked. Two large transcripts were detected in cellulose-grown cells by Northern hybridization: a 14-kb messenger which carries the cipC-cel48F-cel8C-cel9G-cel9E coding sequences and, in a smaller amount, a 12-kb messenger which carries the genes located in the 3' part of the cluster. Four smaller transcripts were found in large amounts: a cipC-cel48F bicistronic one and three monocistronic ones, cipC, cel48F, and cel9E. The cipC-cel48F and cel48F messengers were shown to be stable. Analysis by reverse transcription-PCR suggested transcriptional linkage of all of the open reading frames. The production of a primary very large transcript covering the entire cluster was hypothesized. Primer extension analysis has identified two putative transcriptional start sites located 638/637 and 194 nucleotides upstream of the cipC translational start. The processing of the primary transcript would lead to the production of several secondary messengers displaying different stabilities, contributing to fine tuning of expression of individual genes of the operon.

Small-angle X-ray scattering (SAXS) is an increasingly popular method to obtain low-resolution structures of complex macromolecules and their complexes in solution, in part due to recent technical and computational advances that make this method more and more accessible. However, to obtain unambiguous molecular interpretation from SAXS envelopes, the efficient use of and combination with additional structural methods are crucial. The multimodular character of cellulases and their assemblage in the cellulosome are ideally analyzed by such a combination of structural methods. Here, we describe how information from different sources can be combined with SAXS to determine the molecular organization and we depict the recent advancements and trends that are leading to a more comprehensive picture of the molecular architecture of these multimodular enzymes and their organization in macro-assemblages such as cellulosomes.