Navigation Links
How bacteria integrate autotransporters into their outer membrane

The bacterial outer envelope is densely packed with proteins that form small pores and facilitate the passage of nutrients, toxins and signaling molecules. Professors Timm Maier and Sebastian Hiller from the Biozentrum of the University of Basel now demonstrate how these transporter proteins are integrated into the outer membrane. Using x-ray structural analysis they reveal the structure-function relationship of the protein TamA, which plays an important role in the assembly of transport proteins in the bacterial outer membrane. Their findings have been published recently in the renowned scientific journal Nature Structural and Molecular Biology.

Shuttling proteins from inside the cell to the outside environment is a complex task for Gram-negative bacteria, which are not only surrounded by an inner membrane, but also by an outer membrane barrier for protection against adverse environmental conditions. The bacteria however, can overcome this additional barrier by inserting special transport proteins into the protective outer membrane. In a joint project, Maier and Hiller, both Professors of Structural Biology at the Biozentrum of the University of Basel, provide mechanistic insights into this key process.

The structure of the assembly protein TamA explains its function

An important option for channeling protein domains across the outer membrane are so-called autotransporters. These membrane proteins form a barrel-like structure with a central pore, but they cannot autonomously transport their "passenger domain" across the outer membrane. Specific assembly proteins are required for the folding and integration of autotransporters into the outer membrane. Employing x-ray crystallography, the authors of the study decoded the atomic structure of the autotransporter assembly protein TamA of the intestinal bacterium Escherichia Coli.

"The protein TamA", explains Fabian Gruss, first author and recipient of a Werner-Siemens PhD fellowship, "also forms a barrel with a pore. The pore is closed to the outside by a lid but a particular kink in the barrel wall provides a gate for autotransporter substrates." When an unfolded autotransporter is delivered, TamA hooks onto one end of the substrate polypeptide chain and integrates it step by step via the gate into its own barrel structure. The TamA barrel is thus expanded; the pore widens and opens such that passenger substrates traverse to the exterior. The assembly process ends when TamA releases the autotransporter into the surrounding membrane. "The autotransporter insertion mechanism was previously completely enigmatic for the first time, knowing the structure of TamA, we can now picture how assembly and translocation could function."

Assembly process important for infections

Many pathogens, such as the diarrhea causing Yersinia, Salmonella or the Cholera pathogen, belong to the group of Gram-negative bacteria. With the help of the autotransporter, they release toxins or adhesive proteins to infect their host cells. In their study, Maier and Hiller provide completely new findings about membrane insertion of autotransporters as well as the translocation of their cargo.


Contact: Olivia Poisson
University of Basel

Related biology news :

1. Leading evolutionary scientist to discuss how genome of bacteria has evolved
2. Study by UC Santa Barbara researchers suggests that bacteria communicate by touch
3. Team discovers how bacteria resist a Trojan horse antibiotic
4. From scourge to saint: E. coli bacteria becomes a factory - to make cheaper, faster pharmaceuticals
5. Bacterial shock to recapture essential phosphate
6. Disarming disease-causing bacteria
7. Study shows unified process of evolution in bacteria and sexual eukaryotes
8. Invisible helpers: How probiotic bacteria protect against inflammatory bowel diseases
9. Researchers develop rapid test strips for bacterial contamination in swimming water
10. Bacteria discovery could lead to antibiotics alternatives
11. Agricultural bacteria: Blowing in the wind
Post Your Comments:
(Date:10/2/2015)... , Oct. 02 2015 ... of the "Enforcing the Law Using Biometrics" ... ) has announced the addition of the ... to their offering. --> Research and ... of the "Enforcing the Law Using Biometrics" ...
(Date:9/29/2015)... Sept. 29, 2015 News facts: ... while also saving energy , Minimized design shrinks ... Power Active Mode and embedded Fujitsu PalmSecure authentication enable ... Fujitsu today shows that good things come in ... models to its enterprise desktop and mobile portfolio. Featuring ...
(Date:9/28/2015)... 2015 According to a new ... Product (Scanner & Others), Application (Access Control & Others), ... & Geography Global - Forecast to 2020", published by MarketsandMarkets, ... 3627.90 Million by 2020, at a CAGR of 23.40% ... market data T ables and 66 ...
Breaking Biology News(10 mins):
(Date:10/13/2015)... ... October 13, 2015 , ... Clinovo recently appointed Jeff Parr and ... fast growing clinical data solutions business. , Jeff Parr has spent the past decade ... including Avery Dennison, Thermo Fisher, and Ab Sciex to name a few. He ...
(Date:10/12/2015)... OAKS, Calif. and BRUSSELS , ... UCB (Euronext Brussels: UCB) today presented additional findings from an ... 1 The findings were presented today in an oral ... Research (ASBMR) 2015 Annual Meeting in Seattle ... --> The small exploratory sub-study data ...
(Date:10/12/2015)... -- cell surface marker detection market is ... a new report by Grand View Research, Inc. This growth ... oncology diseases and other cell-associated disorders. --> cell ... 6.49 billion by 2022, according to a new report by ... attributed to rise in incidence of oncology diseases and other ...
(Date:10/12/2015)... offers user-friendly, multi ... --> offers user-friendly, ... online experience --> ... version for enriched online experience Elsevier ... information products and services, announced today that it has ...
Breaking Biology Technology: