Growth of the Stress-Bearing and Shape-Maintaining Murein Sacculus of Escherichia coli

INTRODUCTION .......................................................................................................................................................181 Reinforcement for the Wall ...................................................................................................................................181 MUREIN, A CROSS-LINKED BIOPOLYMER .....................................................................................................181 Structure ..................................................................................................................................................................181 Muropeptide Analysis.............................................................................................................................................183 Length Distribution of Glycan Strands ...............................................................................................................183 Particular Muropeptides........................................................................................................................................184 SYNTHESIS OF THE MUREIN SACCULUS........................................................................................................185 Membrane Translocation of Precursors..............................................................................................................185 Bifunctional Enzymes.............................................................................................................................................185 Transglycosylation ..................................................................................................................................................187 D,D-Transpeptidation: the Target of Penicillin ...................................................................................................187 L,D-Transpeptidation ..............................................................................................................................................187 A BAG-SHAPED EXOSKELETON CALLED THE SACCULUS ........................................................................188 Isolated Murein Sacculi .........................................................................................................................................188 Arrangement of the Glycan Strands ....................................................................................................................188 Murein Surface Density .........................................................................................................................................188 Elasticity of Murein................................................................................................................................................188 MUREIN METABOLISM DURING GROWTH ....................................................................................................189 Cell Elongation and Cell Division........................................................................................................................189 Maturation of Murein ............................................................................................................................................190 Murein Turnover ....................................................................................................................................................191 Murein Recycling ....................................................................................................................................................191 b-Lactamase Induction ..........................................................................................................................................191 GROWTH AND DIVISION OF THE SACCULUS................................................................................................191 Murein Hydrolytic Activity ....................................................................................................................................191 The Problem of Enlarging a Stress-Bearing Structure .....................................................................................191 Speculative Views on the Growth Mechanism of the Murein Sacculus of Gram-Negative Bacteria..........192 Constriction of the Murein Sacculus ...................................................................................................................194 INDICATION FOR A MUREIN-SYNTHESIZING MACHINERY .....................................................................195 Hypothetical Multienzyme Complex.....................................................................................................................195 Control of Potentially Autolytic Enzymes............................................................................................................196 MORPHOGENESIS OF E. COLI ............................................................................................................................197 Cell Cycle of a Rod.................................................................................................................................................197 Maintenance of the Diameter ...............................................................................................................................197 Doubling in Length.................................................................................................................................................197 Possible Regulatory Function of Carboxypeptidases .........................................................................................198 HEREDITY OF STRUCTURAL INFORMATION ................................................................................................198 Is the Murein Sacculus Playing the Role of a Template? ................................................................................198 ACKNOWLEDGMENTS ...........................................................................................................................................200 REFERENCES ............................................................................................................................................................200