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Yet another protein has been added to the crowd of players found at the ends of chromosomes. Known variously as PTOP, PIP1 or TINT1, this negative regulator of telomere length connects some of the key proteins already known to be present – TRF1, TIN2, POT1, and TRF2 – and adds even more complexity to telomere protein interactions.

Homologous recombination in the bacteria cell is regulated at many levels. The central enzyme of homologous recombination RecA and its regulation has been a subject of intense studies by single molecule techniques during the last decade. The RecX protein of Escherichia coli is known to be a negative regulator of RecA. Here we combined optical trapping and microfluidics in order to address the dynamics of RecA-dsDNA filament in the presence of RecX at the single molecule level. Our preliminary results show that RecX blocks elongation of RecA filament and facilitates RecA disassembly from dsDNA in the concentration-dependent manner.The work was carried out with financial support from the Russian Science Foundation (grant No. 14-34-00023) and Russian Foundation for Basic Research (grant No. 13-04-40343-Н).

(Current Biology 21, 520–525; March 22, 2011)In this article, we reported that the AFB4 protein is a negative regulator of auxin response based on the auxin hypersensitivity of the afb4-2 mutant line. Recently we obtained a second afb4 allele and confirmed that it is an RNA null. This mutant is not auxin hypersensitive, indicating that our conclusion that AFB4 is a negative regulator of auxin response is incorrect. For this reason, we wish to retract the article. Other conclusions from the study, including the demonstration that AFB4 and AFB5 are auxin receptors and are the major targets of the synthetic auxin picloram, remain valid. The corresponding author wishes to apologize to the scientific community for any confusion that might have arisen from the study.