Cell size, macromolecular composition and dimensions of Escherichia coli are well correlated with the mean complexity of its nucleoid(s), which is expressed as the ratio between the mean times to replicate the chromosome and to duplicate the cell, C/t , aka the number of replication positions n. Cell Cycle Simulation program (CCSim, described in) has enabled explanation of a set of old, puzzling observations of dimensions, consistent with the view that cell width is determined by n, and that branching results from breaching the maximum possible value nmax . This maximum is interpreted in terms of the "eclipse", a minimal distance possible between successive moving replisomes. The data are subject to analytical quantification designed to model the correlations in a way that may lead to deciphering the primary signal transduced from the nucleoid structure to the biosynthetic pathway of the shape-maintaining peptidoglycan. The physical signal invoked is related to the transcription / translation of membrane protein genes coupled to membrane-insertion of these proteins, so-called "transertion" mechanism. Means to measure the reciprocal stress imposed by transertion strings on both nucleoid and cell envelope are sorely lacking. The recent suggestion that cell length is also determined by n thus forming so-called shape homeostasis, is consistent with data but not with previous analysis. Resolving this inconsistency by comparing model with experimental results (existing as well as newly obtained) may shed light on the necessary coupling between the two unique structures in a bacterial cell, nucleoid and sacculus.

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