The new buzz word is viral; everything goes and grows viral these days- Communication goes viral in an instant, thanks to the internet. But how do the actual biological viruses communicate , or do they communicate at all? First report that they do has appeared in the 26th January issue of Nature.
But that was not the question a team scientists led by Prof. Rotem Sorek, Weizmann Institute asked. They were hoping to intercept bacterial communication. Bacteria are known to share information with descendants and close relatives through chemical messengers. The process is referred to as quorum sensing. These chemical messengers are small peptide molecules whose presence and concentration level in the medium are signals for the bacterial communities to readjust or regulate their behaviour to maximise survival advantage. The team set out to monitor the behaviour of Bacillus subtilis infected with various viruses. Viruses that infect bacteria are called bacteriophages or simply phages. The word phage which has a Greek connection, connotes gobbling up/consuming/annihilating. True, phages can gobble up their bacterial host, but there are times when they refrain from such an extreme step. Here is the full story. A phage infecting a host has two options : either multiply quickly and kill of the host or settle for a live and let live policy temporarily, waiting for an opportune moment. The first one is called lysis (or the lytic pathway) and the second one is lysogeny (or the Lysogenic Pathway). Either way to counter the viral attack bacteria might put in place a defence strategy. The Weizmann team was hoping to idenify and isolate messenger/s which might provide clues on the survival strategies phage infected bacteria might adopt.
The team investigated the growth pattern of Bacillus subtilis infected with 4 different phages: phi29, phi105, rho14 and phi3T. had hoped to spot a chemical messenger or messengers which facilitated bacterial communication. But they were in for a surprise. Analysis of the bacterial broth infected with phi3T yielded a small peptide molecule but it was of viral origin. Follow up studies established it to be a short peptide used by the phi3T phage to communicate within its community, a kind of strategy signal to successive generations. Less of the peptide in the medium prompted the new generation to get on a vigorous lytic phase while more of it in the medium proved to be a warning signal to get onto dormant lysogenic phase. So in reality this was decision making process. Excited, the team gave an appropriate name to the peptide- arbitrium which in latin means decision. The team also observed that during the initial stages of infection when bacteria to phage ratio is high, the concentration of arbitrium in the medium is very low signalling lytic phase. During the later stages of infection when almost all bacterial population is infected, arbitrium levels shoot up signalling new generations of the phages to lie low for the time being.
But that was not the question a team scientists led by Prof. Rotem Sorek, Weizmann Institute asked. They were hoping to intercept bacterial communication. Bacteria are known to share information with descendants and close relatives through chemical messengers. The process is referred to as quorum sensing. These chemical messengers are small peptide molecules whose presence and concentration level in the medium are signals for the bacterial communities to readjust or regulate their behaviour to maximise survival advantage. The team set out to monitor the behaviour of Bacillus subtilis infected with various viruses. Viruses that infect bacteria are called bacteriophages or simply phages. The word phage which has a Greek connection, connotes gobbling up/consuming/annihilating. True, phages can gobble up their bacterial host, but there are times when they refrain from such an extreme step. Here is the full story. A phage infecting a host has two options : either multiply quickly and kill of the host or settle for a live and let live policy temporarily, waiting for an opportune moment. The first one is called lysis (or the lytic pathway) and the second one is lysogeny (or the Lysogenic Pathway). Either way to counter the viral attack bacteria might put in place a defence strategy. The Weizmann team was hoping to idenify and isolate messenger/s which might provide clues on the survival strategies phage infected bacteria might adopt.
The team investigated the growth pattern of Bacillus subtilis infected with 4 different phages: phi29, phi105, rho14 and phi3T. had hoped to spot a chemical messenger or messengers which facilitated bacterial communication. But they were in for a surprise. Analysis of the bacterial broth infected with phi3T yielded a small peptide molecule but it was of viral origin. Follow up studies established it to be a short peptide used by the phi3T phage to communicate within its community, a kind of strategy signal to successive generations. Less of the peptide in the medium prompted the new generation to get on a vigorous lytic phase while more of it in the medium proved to be a warning signal to get onto dormant lysogenic phase. So in reality this was decision making process. Excited, the team gave an appropriate name to the peptide- arbitrium which in latin means decision. The team also observed that during the initial stages of infection when bacteria to phage ratio is high, the concentration of arbitrium in the medium is very low signalling lytic phase. During the later stages of infection when almost all bacterial population is infected, arbitrium levels shoot up signalling new generations of the phages to lie low for the time being.
References:
1.Communication between viruses guides lysis-lysogeny decisions: Erez et al Nature vol541, pages 488-493, January 26, 2017
2. Quorum sensing: cell to cell communication in bacteria: Waters & Bassler : Ann.Rev.Cell Dev.Biol 21:319-46 2005
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