LAUSR

In this work, a comparative analysis of structural organization and biological activity of low-molecular weight ribonucleases (RNases) secreted by Bacillus altitudinis (balnase) and B. licheniformis (balifase) with Bacillus pumilus RNase binase was performed. All three RNases are close homologs; however, binase and balnase differ by only one amino acid residue: polar uncharged threonine at position 106 in the binase molecule is replaced by a non-polar hydrophobic alanine in balnase. RNases share similar physicochemical properties (MW, pI, aliphatic index) but differ in stability of three-dimensional structures that reflects in their ability to inhibit proliferation of cancer cells. Binase forms more stable dimers as compared with balnase and balifase due to the swapping interactions between its molecules that possibly leads to a prolonged antiproliferative effect towards human lung adenocarcinoma A549 cells. The impact of oligomerization in biological effects of RNases is discussed.