Ancient bacteria go under the lens

Every fourth breath you take comes from cyanobac­teria, which pop­u­late the planet’s waters. Prog­en­i­tors of these micro­scopic, pho­to­syn­thetic organ­isms are believed to have been the first organ­isms to release oxygen into the atmos­phere. Their evo­lu­tion nearly 3 bil­lion years ago is thought to have enabled all aer­obic life on Earth.

But the same process that accounts for one quarter of the planet’s breath­able oxygen has also turned cyanobac­teria into one of the most poorly con­trolled forms of water pol­lu­tion, experts say. Rising ocean tem­per­a­tures and acidity have led to dev­as­tating blooms of marine cyanobac­teria around the globe, over­whelming other native species.

Despite these prob­lems, researchers still don’t have an easy way of studying cyanobac­teria through genetic analysis, according to Jacque­line Piret, an asso­ciate pro­fessor of mol­e­c­ular micro­bi­ology. Piret recently co-​​authored a research paper on the sub­ject in the journal Nature along with former stu­dent Desislava Raytcheva and col­leagues at the Mass­a­chu­setts Insti­tute of Tech­nology and the Baylor Col­lege of Medicine.

To over­come these chal­lenges, the research team is inves­ti­gating a virus called Syn5, which infects a cyanobac­te­rial species. “A bac­te­rio­phage virus offers an oppor­tu­nity to engi­neer a vector for car­rying out genetic manip­u­la­tion in the host organism,” Piret explained. By tweaking the host genome through con­trolled viral infec­tion, the researchers can tease out the func­tions of par­tic­ular genes, such as those involved in the har­vest of light energy for photosynthesis.

But in order to use the bac­te­rio­phage to their advan­tage, Piret’s team first needed to under­stand its struc­ture and behavior, as it was still unclear how the virus assem­bled and went on to infect its host.

For her doc­toral dis­ser­ta­tion, Raytcheva used painstaking exper­i­mental tech­niques to work out Syn5’s struc­ture, which turned out to be rather unique in that it has a horn pro­truding from the virus’ exte­rior shell. “Very few other viruses are known to have a sim­ilar struc­ture,” she explained.

In 2009, the researchers at North­eastern and MIT began col­lab­o­rating with their col­leagues at Baylor Col­lege of Med­i­cine, which had devel­oped an advanced microscopy tech­nique. The method allowed them to see in almost real-​​time and with striking clarity the Syn5 assembly process that Raytcheva had pieced together.

Piret noted that the imaging data com­ple­ments Raytcheva’s work, pointing to the two-​​pronged approach to get to the assembly process. “You need phys­ical evi­dence,” she said, “and then you need bio­chem­ical infor­ma­tion about the intermediates.”

This work is an impor­tant step toward under­standing how cyanophages infect and assemble inside their hosts. That knowl­edge, said Raytcheva, will be crit­ical for devel­oping methods for both studying and con­trol­ling cyanobacteria.

The material in this press release comes from the originating research organization. Content may be edited for style and length. Have a question? Let us know.


One email, each morning, with our latest posts. From medical research to space news. Environment to energy. Technology to physics.

Thank you for subscribing.

Something went wrong.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.