Bacteriophage MS2 RNA is 3,569 nucleotides long. The nucleotide sequence has been established for the third and last gene, which codes for the replicase protein. A secondary structure model has also been proposed. Biological properties, such as ribosome binding and codon interactions can now be discussed on a molecular basis. As the sequences for the other regions of this RNA have been published already, the complete, primary chemical structure of a viral genome has now been established.

The 1.4 A resolution structure of recombinant mouse tumour-necrosis factor alpha (mTNF) at 100 K has been determined. The crystals are triclinic, space group P1, with unit-cell parameters a = 48.06, b = 48.18, c = 51.01 A, alpha = 114.8, beta = 103.6, gamma = 91.1 degrees. The structure was refined to a final crystallographic R value of 19.7% (Rfree = 23.3%), including 3477 protein atoms, one 2-propanol molecule, one Tris molecule and 240 water molecules. Throughout the crystal lattice, the trimers are differently packed compared with human TNF, which was crystallized in the tetragonal space group P41212 and refined to 2.6 A resolution. The structures of mTNF and human TNF are very similar, diverging mainly in regions that are either flexible and/or involved in crystal packing. Some loops in mTNF which contain residues important for receptor binding are better resolved than in human TNF, such as the surface-exposed loops 30-34 and 144-147, which are also important for receptor specificity. Compared with human TNFs, the channel formed by the three monomers in mTNF is narrower. One 2-propanol molecule trapped in the trimeric channel could be a lead compound for the design of TNF inhibitors.

Secretion of functional recombinant murine interleukin-2 (mIL2) by Lactococcus lactis was achieved by fusion of the sequence encoding mature mIL2 to the secretion signal leader of the lactococcal usp45 gene placed under transcriptional control of the phage T7 promoter-T7 RNA polymerase expression system. The recombinant mature mIL2 was one of only a few proteins which accumulated in the growth medium. Sequence analysis revealed correct processing at the first amino acid of the mature protein. A T-cell proliferation assay showed that the recombinant protein has the same specific biological activity as mIL2 obtained from a natural source.

No abstract