Operon structure

D. Variation of Operon Structure in the Citric Acid Cycle. 373... 

Romling, U., Bain, Z., Hammar, M., Sierralta, W. D., and Normark, S. (1998). Curli fibers are highly conserved between Salmonella typhimurium and Escherichia coli with respect to operon structure and regulation. /. Bacteriol. 180, 722-731. 

Rahlfs S, Aufurth S, Muller V. 1999. The Na -FiFo-ATPase operon from Acetobac-terium woodiv. operon structure and presence of multiple copies of atpE, which encode proteolipids of 8- and 18-kDa. J Biol Chem 274 33999 004. 

Fig. 7 Genes coding for PVA degradations are organised in an operon structure. The scheme (simplified from Kawai [70]) shows the situation in two well-studied PVA-degrading strains Pseudomonas and Sphingopyxis). The genetic organisation in other strains has not yet been examined in such detail...

Nierhaus and his colleagues [168] have suggested that in E. coli the r-proteins which form part of an operon constitute assembly units. Thus, the order of the r-protein genes seems to be important for the assembly of the ribosome in those organisms in which the synthesis of r-proteins and the assembly of the ribosome take place in a single compartment. Since this is also the case with the archaea, it is perhaps for this reason that the gene order has been conserved in both domains for efficient ribosome production. In the eucarya, however, where synthesis and assembly take place in different cell compartments, the order in which the r-proteins are synthesized might be of less importance and the operon structure has not been conserved. 

Nicosia A, Perugini M, Franzini C, etal. (1986) Cloning and sequencing of the pertussis toxin gene operon structure and gene duplication. In Proc. Natl. Acad. Sci. USA 83 4631 -4635. 

When the cell has an adequate supply of glucose, the level of cAMP is low. GAP binds to the promoter only when it is complexed to cAMP. The combination of positive and negative regulation with the lac operon means that the presence of lactose is necessary, but not sufficient, for transcription of the operon structural genes. It takes the presence of lactose and the absence of glucose for the operon to be active. As we shall see later, many transcription factors and response elements involve the use of cAMP, a common messenger in the cell. 

The catabolite activator protein is a transcription factor in E. coli that stimulates transcription of the lac operon structural genes. It responds to cAMP levels such that the lac operon is transcribed only when the cells must use lactose as a fuel source. 

S. (2002) Correlations between Shine-Dalgarno sequences and gene features such as predicted expression levels and operon structures. 

The lac operon in the bacterium Escherichia coli is a well-studied GRN. This prokaryotic gene network has been the subject of numerous reviews it is discussed here primarily to illustrate the various aspects of GRN modeling, starting with the information on genome organization (operon structure) to knowledge on protein-DNA interactions, protein-protein interactions, and the influence of metabolites. 

Fig. 16. Models of operon structure in eukaryotes. A. (From Scherrer and Marcaud. 1968. J. Cell. Physio ., 72 (Suppl. 1) 181-212.) B. (From Britten and Davidson. 1969. Sb/e/ice, 165 349-357.) C. (From Georgiev. 1969. J. Theor. S/o/., 25 473-490.)...

---