VirA disrupts microtubules (green) and causes membrane ruffling.

杨柳

Many invasive bacteria let themselves into host cells, not bothering to wait for an invitation. So far, known effector proteins that allow bacteria to enter work by rearranging actin dynamics. But new research from Sei Yoshida, Chihiro Sasakawa (University of Tokyo, Tokyo), and colleagues reveals that Shigella bacteria have another trick up their proverbial sleeves. They destabilize microtubules (MTs) to promote their own phagocytosis.7 E. e( R- p' u3 ^
4 O( `/ Q- {+ T/ [' I5 S0 J
Shigella uses the Type III secretion system to deliver a set of its effector proteins into cells it plans to invade. Some of these proteins act in well-known ways to modulate the actin cytoskeleton. For instance, IpaA binds the focal adhesion protein vinculin, and this complex promotes actin depolymerization. But the group focused on VirA, which acts independently of other effectors. Shigella lacking VirA are 70–80% less invasive than wild-type bacteria.
0 ?+ \6 P9 w1 V
+ |5 Q$ W' {, t' t/ ^& y) `# oThe authors found that VirA bound /?-tubulin heterodimers and destabilized MTs in vitro and in vivo. Destabilization led to membrane ruffling around the bacterium, an effect that was dependent on the activation of Rac1. Sasakawa is not yet sure how VirA binding causes MT instability. Bound heterodimers may be held less stably in the MT lattice, or VirA might compete with MTs for binding to tubulin heterodimers. VirA homologues exist in other bacteria, including E. coli, indicating that a wide range of pathogens may alter MT dynamics to aid in their invasion.
. C$ W4 H! K; t: G( b6 s: e% O4 e
' w" Z5 c2 C5 G7 u3 fReference:
0 t; |" N# A" C. `0 O3 R6 }2 M* Z) F
Yoshida, S., et al. 2002. EMBO J. 21:2923–2935.(Sasakawa/EMBO)

龙水生

快毕业了 希望有个好工作 干细胞还是不错的方向

tempo

呵呵,支持一下哈  

石头111

进行溜达一下  

剑啸寒

@,@..是什么意思呀？  

aakkaa

来几句吧  

yukun

干细胞之家 我永远支持

我心飞翔

干细胞我这辈子就是看好你

marysyq

干细胞从业人员  

marysyq

一个人最大的破产是绝望，最大的资产是希望。