Search PubMed⌕ Search

Biomedical subjects

K J Begg

Publications and source records attributed to K J Begg.

29 records · Page 2Linked to original sources
PubMed1979

Role of the ftsA gene product in control of Escherichia coli cell division.

The kinetics of cell division have been studied in a strain of Escherichia coli which has an amber mutation in the ftsA gene and which also carries a temperature sensitive amber suppressor. This strain is therefore temperature sensitive for the synthesis of the ftsA protein. Cells of this strain were able to divide only if the synthesis of this protein took place during a specific part of the cell cycle. This was a short period (roughly 10 min in duration) immediately before the normal time of cell division.

Bacterial Proteins↗
PubMed1978

Changes in cell size and shape in thymine-requiring Escherichia coli associated with growth in low concentrations of thymine.

Thymine auxotrophs of three unrelated strains of Escherichia coli (K-12, B/r, and 15) were grown in media containing various concentrations of thymine. During steady-state growth conditions, cell volume increased as thymine concentration decreased but, in contrast to previous reports, this change was due to an increase in cell length without change in cell diameter.

Cell Count↗
PubMed1978

Cell surface growth in Escherichia coli: distribution of matrix protein.

Autoradiography of cell envelope "ghosts" from Escherichia coli was used to demonstrate that newly synthesized molecules of "matrix" protein are inserted at random locations over the entire surface of the outer membrane and that, once inserted, these molecules are not thereafter conserved in any fixed spatial location.

Bacterial Proteins↗
PubMed1977

Growth of the Escherichia coli cell surface.

Phage T6 was used as a label to follow the growth of the outer membrane in a strain of Escherichia coli temperature sensitive for the production of the T6 receptor. Extension of the surface takes place at the cell poles. Small cells extend at only one pole, whereas larger cells grow from both poles. The change from unipolar to bipolar growth appears to depend on the attainment of a particular cell size and not on completion of chromosome replication.

Cell Membrane↗
PubMed1976

Cell length, cell growth and cell division.

When cells of E. coli reach a certain critical length, which is constant in all growth conditions and eqqal to twice the minimum cell length, they abruptly increase their rate of elongation and divide about 20 min later. Chromosome replication terminates at about this same cell length but is not the signal for the change in rate of cell elongation.

Cell Division↗
PubMedDate not supplied

Structure and function of the ftsH gene in Escherichia coli.

The ftsH mutant Y16 shows thermosensitive filamentation with reduced amounts of penicillin-binding protein 3 (PBP3) (Ferreira et al., 1987). Genetic analysis, however, showed that the lethality of the ftsH mutation was not due to a lack of PBP3 activity alone. The ftsH gene was cloned and sequenced and the FtsH protein was deduced to be a membrane protein of 70.7 kDa which has an ATP-binding domain. Highly significant homology of amino acid sequence was observed between FtsH protein and two eukaryotic proteins, yeast Saccharomyces cerevisiae Sec 18p and its mammalian homologue NSF, which are involved in protein transport pathways. This suggests that FtsH protein may act for translocation of specific proteins including PBP3 and at least one other additional protein essential for cell growth. Suppressor mutants of Y16, which were able to grow at 42 degrees C, were isolated, and the suppressor mutations (sfh) were mapped to 16 min. A wild type chromosomal fragment able to complement the sfh mutations was cloned. We also identified another gene (ftsJ) affecting cell division in the region upstream of the ftsH gene.

Bacterial Proteins↗
PubMedDate not supplied

Isolation and characterization of intragenic suppressors of an Escherichia coli ftsA mutation.

Mutagenesis of a strain of Escherichia coli carrying a temperature-sensitive (Ts) mutation in the cell division gene ftsA yielded a number of temperature-resistant variants. In certain cases, restoration of viability at the restrictive temperature could not be attributed to suppressor mutations occurring in other genes or to structural gene reversion. DNA sequencing of the variants demonstrated the continuing presence of the original Ts mutation (ftsA13) and revealed secondary mutations within the same gene. These secondary mutations are able to rescue the ftsA13 mutation in cis, but not in trans.

Autoradiography↗