Navigation Links
Biochemists find incomplete protein digestion is a useful thing for some bacteria

AMHERST, Mass. Usually indigestion is a bad thing, but experiments by researcher Peter Chien and graduate student Robert Vass at the University of Massachusetts Amherst recently showed that for the bacteria Caulobacter crescentus, partial degradation of a DNA replication protein is required to keep it alive.

DNA replication is one of the most highly controlled biological processes in all organisms, says Chien, an assistant professor of biochemistry and molecular biology at UMass Amherst. From humans all the way back to bacteria, all cells must faithfully duplicate their genomes in order to survive. To coordinate the start, ensure the completion and repair damages during DNA replication, specialized proteins play a key role by regulating processes.

In work published this month in Proceedings of the National Academy of Sciences, Chien and Vass report that one of these specialized replication factors, DnaX, is, to their surprise, partially digested or trimmed, physically cut into shorter fragments, by an energy-dependent protease known as ClpXP, which generates specific-sized fragments that are essential for Caulobacter's normal growth.

The phenomenon isn't entirely unknown, Chien explains. Short as well as long versions of DnaX had been observed 20 years ago in another bacteria, E. coli. But in E. coli, the short form was produced by changes in translation due to an early ribosome stop at a specific RNA sequence. That RNA sequence is absent in many bacteria DnaX genes including in Caulobacter, so scientists long thought that short DnaX only existed in bacteria like E. coli.

Based on previous studies in his lab, Chien and Vass moved on to investigate, by purifying these proteins and testing their activity in Caulobacter in vivo, whether the protein DnaX could be degraded by the protease ClpXP. To their surprise, ClpXP did recognize DnaX, but only partially degraded it, generating stable shorter fragments both in vitro and in vivo.

Further, they found that both long and short forms were essential for normal growth and that the short form was particularly important for DNA damage tolerance, suggesting that these fragments are not accidental but are made in a programmed manner.

Vass and Chien's new work shows that in some bacteria, short forms of DnaX are made instead by another method, proteolysis, with dramatic consequences for the cell, the biochemist says. "This type of convergent evolution results in similar protein outcomes, that is the generation of two forms through radically different mechanisms. This suggests that both long and short forms are crucial for all bacteria," he adds.

Protein degradation by energy-dependent proteases normally results in the complete destruction of target proteins, Chien notes. However, under particularly harsh artificial conditions in the test tube, these proteases can stall on certain targets. But until the recent UMass Amherst experiments, such an effect had never been seen inside a living bacterial cell, he adds.

Chien feels this mode of partial digestion could be useful in other bacteria to generate new functions from existing proteins and increasing the ability of a single gene to encode for multiple protein functions. This work was supported by NIH's National Institute for General Medical Sciences and by UMass Amherst.


Contact: Janet Lathrop
University of Massachusetts at Amherst

Related biology news :

1. UMass Amherst biochemists developing tools to stop plague and other bacterial threats
2. Biochemists uphold law of physics
3. IU biologists offer clearer picture of how protein machine systems tweak gene expression
4. Making memories: How 1 protein does it
5. Embryonic development protein active in cancer growth
6. More effective method of imaging proteins
7. The loss of a protein makes jump the tumor to the lymph node
8. Gold nanoantennas detect proteins
9. The Japanese traditional therapy, honokiol, blocks key protein in inflammatory brain damage
10. New hope for treating Alzheimers Disease: A role for the FKBP52 protein
11. Protein jailbreak helps breast cancer cells live
Post Your Comments:
Related Image:
Biochemists find incomplete protein digestion is a useful thing for some bacteria
(Date:4/26/2016)... and LONDON , April 26, ... of EdgeVerve Systems, a product subsidiary of Infosys ... announced a partnership to integrate the Onegini mobile ...      (Logo: ) ... customers enhanced security to access and transact across ...
(Date:4/19/2016)... April 20, 2016 The new ... a compact web-based "all-in-one" system solution for all door ... reader or the door interface with integration authorization management ... control systems. The minimal dimensions of the access control ... the building installations offer considerable freedom of design with ...
(Date:4/15/2016)... , April 15, 2016 ... the,  "Global Gait Biometrics Market 2016-2020,"  report to ... ) , ,The global gait biometrics ... of 13.98% during the period 2016-2020. ... angles, which can be used to compute factors ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... ... June 23, 2016 , ... Supplyframe, ... of the Supplyframe Design Lab . Located in Pasadena, Calif., the Design ... of how hardware projects are designed, built and brought to market. , The ...
(Date:6/23/2016)... BEACH, Calif. , June 23, 2016  Blueprint ... new biological discoveries to the medical community, has closed ... co-founder Matthew Nunez . "We have ... us with the capital we need to meet our ... will essentially provide us the runway to complete validation ...
(Date:6/23/2016)... ... June 23, 2016 , ... Regulatory ... technical consulting, provides a free webinar on Performing Quality Investigations: Getting ... at 12pm CT at no charge. , Incomplete investigations are still a major ...
(Date:6/22/2016)... June 22, 2016 Cell Applications, Inc. ... them to produce up to one billion human ... within one week. These high-quality, consistent stem cells ... cells and spend more time doing meaningful, relevant ... proprietary, high-volume manufacturing process that produces affordable, reliable ...
Breaking Biology Technology: