Part:BBa_K2912000

RebA may act as a scaffolding protein to facilitate the major polymerization process

2019 SZU-China

Biology

SZU-China 2019 iGEM team was going to find a suicide switch inside the E coli that can break the whole body of the bacteria leading to the release of RNAi molecules transcribed from E coli inducing by IPTG or some others. Therefore, we were in need of a useful mechanism. Fortunately, we finally found the Refractile inclusion bodies (R-bodies) to kill the E coli, causing the inclusion to flow out of the plasma membrane so that we can get the RNAi molecules transcribed by E coli.

Refractile inclusion bodies, known as R bodies, are produced by only a few species of bacteria. These inclusion bodies are highly insoluble protein ribbons, typically seen coiled into cylindrical structures within the cell[1]. R-bodies are produced by Paramecium endosymbionts belonging to the genus Caedibacter. These intracellular bacteria confer upon their hosts a phenomenon called the killer trait[2]. This is one of the DNA sequences for the R body locus (reb) from Caedibacter taeniospiralis. It has been suggested that Reb A may act as a scaffolding protein to facilitate the major polymerization process. The identity in amino acid sequence between Reb A and Reb B suggests a similar structure and function. Like Reb B, Reb A is modified into two or more species with different molecular weights before the major polymerization event occurs[3].

Comparison of the hydropathy plots for Reb B with those for Reb A suggests a similar secondary structure for these regions. Therefore, Reb A should be capable of entering either a temporary or permanent association with the polymerized complexes of Reb B. If the acidic Reb A proteins are linked to the growing R body complex (as scaffolding or at the site of polymerization), they may be responsible for the increased pIs during the major polymerization event. That is, the proportional contribution of Reb A may decline as polymerization proceeds, resulting in a shift of the pls. Pulse-chase analysis of the protein products encoded by pBQ65 reveals that, like Reb B, the modified faster-migrating species of Reb A decrease in concentration over time as the higher-molecular-weight polymerization complexes are formed. This is evidence that Reb A proteins may associate directly with the polymerization complexes[3].

The R bodies of C. taeniospiralis are type 51. They are about 0.5 μm wide, have a maximum length of 20 μm, and 13 nm thick, possess acute angles at each end and unroll in a telescopic fashion when exposed to a pH of 6.5 or lower. These proteinaceous ribbons are rolling up inside the cell to form a hollow cylinder about 0.5 μm in diameter and 0.5 μm long[4]. For more information, please see BBa_K2912017-R-body.

Sequence

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]