An Osmotic Sensor Governing Cell Division And Development Of Cell Wall In Arthrobacter

Arthrobacter sp. strains are among the most frequently isolated, indigenous, aerobic bacterial genera found in soils. It could degread pollutants and generated bio-energy such as hydrocarbons. Arthrobacter sp. strains have been found to be the strongest stress trolence microbiology. In response to osmotic stress and drought stress, the performances of Arthrobacter sp. strains were even better. Therefore, the current researches for this type of micro-organisms come to hot topic. However, the molecular mechanism of stress tolerance still unknown.Transitory myceloid growth occurs in certain high salt stress media with Arthrobacter strain A3. And we also found the same phenotype of trehalose 6-phosphates synthase (otsA) knockout strain. This aggregation was mainly due to the failure to separate the split Arthrobacter cell walls after division. Additionally, the otsA knockout strain and the wild strain, grown in high osmotic pressure conditions, have shown the same phenomenon:the generation times are significantly higher than that of wild type grown in LB medium.The influence of growth rate of otsA mutant is neither caused by the steric hindrance nor due to the lack of trehalose. OtsA missing could lead to failure form the division complex. The location of nascent cell wall ring is necessary for division site. Therefore, knock out of otsA can grow slowlyOtsA could interact with FtsZ directly and could promote FtsZ polymerization in vitro. FtsZ is actin-like proteins in bacteria and is a necessary condition for division in most bacteria. Additionally, the polymerization of FtsZ ring wall necessary for the formation nascent cell wall ring. OtsA can promote the polymerization of FtsZ ring structure and lead to form nascent cell wall ring in vivo. In the otsA knockout strain, the polymerization of FtsZ will be affected. Therefore, the division rate was affected by the OtsA content.OtsA aggregated into polymers and the monomeric protein is not present in vivo. There is no levels change of OtsA and FtsZ during salt stress. The highest polymerization state of OtsA decreased gradually as the strain subjected salt stress. The changes of high polymer state of FtsZ have the same trends with OtsA high polymer. High polymers state of OtsA may be formed complex with FtsZ and promote FtsZ polymerization. Salt stress can promote depolymerization of OtsA thus reducing FtsZ polymerization. The enzyme activity OtsA is essential for the polymerization of FtsZ in vivo. Salt stress inhibited the formation of nascent cell wall ring in vivo and it may be the reason for slow growth rate of Arthrobacter when grown in high salt medium. Salt stress could lead depolymerization of OtsA and promote the none-uniform spiral-like structure present between the poles and the nascent cell wall ring which may be the reason for forming clump.The surface structure of cell wall of wild type strain living in LB was interwoven by the uniform size of particles and has a certain texture. When theâ–³otsA strain grown in LB, the cell wall was very fragile and became to fragments after the extraction of cell wall. From the surface structure of cell wall, we can see the sizes of particles are non-uniform, while the texture is not interwoven. The cell wall surface structure of ectopically expression of OtsA strain living in LB is very smooth. The interwoven manner of cell wall particles is an important way to respond to salt stress. The migration of nascent cell wall and surface structure of the cell wall morphological changes the same during salt stress. The non-uniform of nascent cell wall can cause thickness of wall which is difficult to separate, leading to forming clump.In summary, salt stress can lead the depolymerization of OtsA and resulting in decreased FtsZ polymerization. Therefore, the formation of nascent cell wall ring is failure and ultimately grows in slow. The non-uniform of nascent cell wall can cause thickness of wall which is difficult to separate, leading to forming clump. This is the first time to find the osmotic stress receptors in bacteria, and the resilience of the molecular mechanism of receptor regulation. This article offers important theoretical basis which interpret the stress resistance molecular mechanisms of micro-organisms who living in extreme environmental.