M. Zahalak et al., EXPRESSION OF THE MOVEMENT PROTEIN OF TOBACCO MOSAIC-VIRUS IN THE CYANOBACTERIUM ANABAENA SP STRAIN PCC-7120, Molecular plant-microbe interactions, 8(2), 1995, pp. 192-199
The movement protein (MP) of tobacco mosaic virus (TMV) alters the str
ucture and function of the plasmodesmata, the intercellular communicat
ion channels in plants. cDNA encoding the TMV MP was cloned in a cyano
bacterial shuttle vector and transferred to Anabaena sp. strain PCC 71
20. MP was synthesized in Anabaena sp. strain PCC 7120 from the tac pr
omoter and was induced severalfold by addition of the lac inducer IPTG
. Immunoblot analysis of subcellular fractions obtained from IPTG-indu
ced vegetative cells indicated that MP was highly enriched in the cell
wall and the cytoplasmic membrane fractions. High level of MP express
ion prevented diazotrophic growth and new heterocyst differentiation i
n cultures of Anabaena sp. strain PCC 7120. Although expression of MP
in undifferentiated filaments did not inhibit growth, these filaments
could not form heterocysts when subsequently deprived of combined nitr
ogen. Wild-type cells or cells containing the shuttle vector lacking t
he MP gene grew normally and differentiated heterocysts in the presenc
e of IPTG. These results are consistent with the idea that interaction
of MP with components in the cells of Anabaena sp. strain PCC 7120 pe
rturbs normal cell-to-cell communication in the filaments, thereby pre
venting heterocyst differentiation and diazotrophic growth.