Preliminary inquiry of cytoskeleton evolution
— pei cong
? Definationa system of intracellular filaments crucial for cell shape, division, and function in all three domains of life.
CompositionMicrotubules (tubulin), actin filaments and intermediate filaments.
? micro filament
? Initially, there is no physical structure in the cytoplasm, many phenomena of livings such as cell movement, cell shape maintain being hard to explain. ? In 1928, put forward the original concept of cytoskeleton .
? In 1954, the microtubules in the cell was seen under the electron microscope for the first time. ? At this point, the electron production can only use osmic acid and potassium permanganate in low down fixed temperature conditions. ? Cytoskeleton often depolymerized under this condition,thus destroyed.
In 1963, after being fixed in use of glutaraldehyde at room temperature cytoskeleton was widely observed and formally named as a kind of organelles.
Bacterial, archaeal, and eukaryotic cytoskeletons.
Observation of cytoskeleton
? Two-Photon Laser Scanning Microscopy.
? Confocal microscopic observation . ? Elasticity mapping of living fibroblasts by AFM and immunofluorescence .
? About 20 years ago, the discovery that bacteria possess homologues of both tubulin.
? Since that time, the idea that both bacteria and archaea have active and dynamic cytoskeletons.
? So far as, it has been found in bacteria FtsZ, MreB and CreS three important cytoskeleton proteins.
? Respectively be similar to tubulin, actin filament and intermediate filament of eukaryotic cells skeleton .
FtsZ ---- tubulin-related proteins ? a new filamentous thermal sensitivity gene PAT84 Z (filamentous temperature sensitive gene Z, ftsZ) exists in a mutant strains of E. coli. ? Regulate bacterial cell division, and being similar to eukaryotic cell microtubule protein structure and function.
? In the early 1990s scientists point out that FtsZ can be prokaryotic analogues .
? The homology of the sequence is low (< 20%). ? Amino acid sequence G G G T G T G is similar. ? Form strand (protofilament) and microtubules (microtubule) structure.
Z ring structure update about 9 s , which is about 3 times than tubulin .
assemble structure diagram
Function of FtsZ
? In eukaryotes, cell division is mainly composed of actin filament to adjust. microtubule protein is mainly involved in controlling cell morphogenesis. ? In prokaryotes,on the controry , protein FtsZ is the regulation of cell division.
MreB---the actin superfamily
? A rod cell morphogenesis related genes.
? The most common prokaryotic homologue actin . ? As for tubulin/FtsZ, actin and MreB are very divergent in primary sequence but have similar structures.
? In 1992, Bork for the first time put forward eukaryotic