We have constructed chimeric papillomavirus-like particles (CVLPs) by replacing the 34-carboxy-terminal amino acids of the HPV 16 L1 protein with various parts of the HPV 16 E7 protein. Chimeric proteins were expressed by recombinant baculoviruses and analyzed by electron microscopy for their ability to assemble into virus capsids. We were able to produce CVLPs in high efficiencies with inserts of up to 60 amino acids. CVLPs are able to induce a neutralizing antibody response, assayed by inhibition of hemagglutination of mouse erythrocytes. CVLPs are interacting with the putative receptor for papillomaviruses as they were shown to hemagglutinate mouse red blood cells and bind to and penetrate cells in vitro. As CVLPs follow a similar intracellular pathway as observed earlier for BPV VLPs, we speculate that CVLPs can be used to deliver peptides into mammalian cells in vitro and in vivo, possibly reaching the pathway for MHC class I presentation.

Maltodextrin glycoslyltransferase (4-a-glucanotransferase) of the extremely thermophilic ancestral bacterium Thermotoga maritima has been purified from an Escherichia coli clone expressing the corresponding T. maritima MSB8 chromosomal gene. T. maritima 4-a-glucanotransferase, an approximately 53-kDa monomeric enzyme, is the most thermophilic glycosyltransferase described to date. It retained more than 90% of its maximum activity at temperatures from 55°C up to 80°C.The proposed action modus is the transfer of 1 ,4-a-glucanosyl chains, thus resulting in the disproportionation of 1 ,Ca-glucans. It converted soluble starch, amylopectin, and amylose, thereby changing the iodine staining properties of these substrates. The addition of low-molecular-mass maltooligosaccharides, which act as glucanosyl acceptor molecules, enhanced the reaction and resulted in the formation of a series of linear maltohomologues from two to more than nine glucose units in size. Use of either of the malto-oligosaccharides maltotetraose, maltopentaose, maltohexaose, or maltoheptaose as sole substrate also yielded linear maltohomologues. On the other hand, maltose and maltotriose were not disproportionated by 4-a-glucanotransferase, although both were good acceptors for glucanosyl transfer. Glucose did not function as an acceptor in transfer reactions. Glucose also never appeared as a reaction product. The chain length of glucanosyl segments transferred ranged from two to probably far more than six glucose residues.Comparison of the N-terminal amino acid sequence of 4-a-glucanotransferase with other published protein sequences revealed significant similarity to sequences near the N-termini of various eucaryotic maltases and bacterial cyclodextrin glycosyltransferases, suggesting its relatedness on the molecular level with other starch-and maltodextrin-converting enzymes.The extreme environment inhabited by Thermotoga maritima (growth range 55-80°C with an optimum at 80°C [l]) has imposed severe selective pressure upon this microorganism's enzymatic outfit which must be thermophilic as well as thermostable enough to guarantee survival at very high temperatures. Therefore, T. maritima seems to be a profitable source for the iolation of highly thermostable enzymes whose biochemical and structural analysis may be extremely helpful in the task of unraveling the molecular basis of thermostability. Additionally, the thermophilic enzymes produced by this organism may prove to be valuable catalysts for industrial applications.We have isolated the gene for an interesting starch-converting enzyme of T. maritima from a gene library of this organism constructed in E. coli and have purified and charac-

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