Aquaporin tetramer composition modifies the function of tobacco aquaporins.

Heterologous expression in yeast cells revealed that NtAQP1, a member of the so-called PIP1 aquaporin subfamily, did not display increased water transport activity in comparison with controls. Instead, an increased CO(2)-triggered intracellular acidification was observed. NtPIP2;1, which belongs to the PIP2 subfamily of plant aquaporins, behaved as a true aquaporin but lacked a CO(2)-related function.

Polar accumulation of the metabolic sensory histidine kinases DcuS and CitA in Escherichia coli.

Signal transduction in prokaryotes is frequently accomplished by two-component regulatory systems in which a histidine protein kinase is the sensory component. Many of these sensory kinases control metabolic processes that do not show an obvious requirement for inhomogeneous distribution within bacterial cells. Here, the sensory kinases DcuS and CitA, two histidine kinases of Escherichia coli, were investigated.

Detection of single oxygen molecules with fluorescence-labeled hemocyanins.

This study introduces a method to detect individual oxygen molecules by fluorescence microscopy of single hemocyanins. These respiratory proteins from a tarantula bind oxygen with high affinity. A spectrometric signature of the oxygenated protein is transferred to an attached fluorescence label, which can be detected at the single-molecule level.