Mutua Madrileña Foundation, Fondation de l'Université de Lausanne et Centre Hospitalier Universitaire Vaudois, Instituto Carlos III, CIBERER, National Institutes of Health, Generalitat de Catalunya, Fundació CELLEX.

This detailed clinical reference dataset will greatly facilitate diagnostic confirmation and management of patients, and has provided important insights into disease pathogenesis. Ann Neurol 2018;83:1105-1124.

The terminase of bacteriophage SPP1, constituted by a large (G2P) and a small (G1P) subunit, is essential for the initiation of DNA packaging. A hexa-histidine G2P (H6-G2P), which is functional in vivo, possesses endonuclease, ATPase, and double-stranded DNA binding activities. H6-G2P introduces a cut with preference at the 5-RCGG2CW-3 sequence. Distamycin A, which is a minor groove binder that mimics the architectural structure generated by G1P at pac, enhances the specific cut at both bona fide 5-CTATTGCGG2C-3 sequences within pacC of SPP1 and SF6 phages. H6-G2P hydrolyzes rATP or dATP to the corresponding rADP or dADP and P i . H6-G2P interacts with two discrete G1P domains (I and II). Full-length G1P and G1P⌬N62 (lacking domain I) stimulate 3.5-and 1.9-fold, respectively, the ATPase activity of H6-G2P. The results presented suggest that a DNA structure, artificially promoted by distamycin A or facilitated by the assembly of G1P at pacL and/or pacR, stimulates H6-G2P cleavage at both target sites within pacC. In the presence of two G1P decamers per H6-G2P monomer, the H6-G2P endonuclease is repressed, and the ATPase activity stimulated. Based on these results, we propose a model that can account for the role of terminase in headful packaging.Initiation of packaging of double-stranded viral DNA (dsDNA) 1 involves the specific interaction of the prohead with viral DNA in a process mediated by a phage-encoded terminase protein (1-4). The terminase enzymes are usually hetero-oligomers composed of a small and a large subunit. The role of the terminase small subunit is to specifically recognize the packaging initiation site (cos or pac) and to form a nucleoprotein structure that helps to position the terminase large subunit to cleave at the pac or cos site (1-6). Two general principles for packaging of concatemeric DNA into a virus head have been proposed. The first implies a site-specific packaging that shows some constraint in DNA size, in which the recognition sequence (termed cos in phage ) plays an important role in initiation and termination of packaging. This packaging process is wellcharacterized in coliphages , T3, and T7 (1-6). The second principle implies headful packaging, in which the packaging initiates at a specific site (termed pac in phage SPP1) but with the capacity of the prohead playing a predominant role in the termination step. Within the poorly characterized headful packaging mechanism, phages P1, P22, T4, and SPP1 are included (1, 3, 7).The terminase enzyme of Bacillus subtilis phages SPP1 and SF6 is composed of a small (G1P) and a large (G2P) subunit (8). The terminase initiates unidirectional DNA packaging from a concatemeric DNA substrate by binding to pac DNA, introducing a 1-bp staggered cut, within the 83-bp pacC subsite, and encapsidating the DNA from the cleaved end into an empty prohead until no more DNA can be inserted (headful) (8 -11). DNA packaging terminates when the DNA inside the prohead is separated from the concatemer by a cutting process (headful cut). The headful cleavage...

The toxin-antitoxin operon of pSM19035 encodes three proteins: the v global regulator, the e labile antitoxin and the stable f toxin. Accumulation of f toxin free of e antitoxin induced loss of cell proliferation in both Bacillus subtilis and Escherichia coli cells. Induction of a f variant (fY83C) triggered stasis, in which B. subtilis cells were viable but unable to proliferate, without selectively affecting protein translation. In E. coli cells, accumulation of free f toxin induced stasis, but this was fully reversed by expression of the e antitoxin within a defined time window. The time window for reversion of f toxicity by expression of e antitoxin was dependent on the initial cellular level of f. After 240 min of constitutive expression, or inducible expression of high levels of f toxin for 30 min, expression of e failed to reverse the toxic effect exerted by f in cells growing in minimal medium. Under the latter conditions, f inhibited replication, transcription and translation and finally induced death in a fraction (~50 %) of the cell population. These results support the view that f interacts with its specific target and reversibly inhibits cell proliferation, but accumulation of f might lead to cell death due to pleiotropic effects.

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