Practice question

In rod shaped bacteria elongation before division mediated by elongasome or Rod complex distinct from divisome. Core organizer is MreB actin homolog that forms short dynamic patches moving around cell circumference perpendicular to long axis. Motion driven by peptidoglycan synthesis not treadmilling alone, powered by RodA transglycosylase activity. MreB interacts with integral membrane proteins MreC, MreD, RodZ cytoplasmic tail linking to peptidoglycan synthases RodA transglycosylase from SEDS family polymerizing lipid II glycan strands and PBP2a PBP2 transpeptidase crosslinking peptides. Additional components PBP1A class A bifunctional, Rod complex proteins also include MreB associated proteins and cytoskeletal linkers. Together complex inserts new peptidoglycan in circumferential hoops ensuring length increase while maintaining constant diameter. Upon assembly of FtsZ ring at midcell MreB delocalizes, elongasome disassembles, divisome takes over septal synthesis. Unlike FtsZ FtsA division proteins, ParA ParB partition machinery, MinC MinD division inhibition system, elongasome specifically composition MreB and associated proteins responsible for rod elongation coordinating shape with growth rate and protecting from osmotic lysis.