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How bacteria create a piggy bank for the lean times – Phys.org

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Cyanophycin biosynthesis looks like a windshield wiper in action: one domain is responsible for adding aspartate (Asp), a second domain is responsible for adding arginine (Arg), two nitrogen-rich amino acids, and the third domain holds on to the growing chain of cyanophycin. Credit: Schmeing lab

Bacteria can store extra resources for the lean times. It’s a bit like keeping a piggy bank or carrying a backup battery pack. One important reserve is known as cyanophycin granules, which were first noticed by an Italian scientist about 150 years ago. He saw big, dark splotches in the cells of the blue-green algae (cyanobacteria) he was studying without understanding either what they were or their purpose. Since then, scientists have realized that cyanophycin was made of a natural green biopolymer, that bacteria use it as a store of nitrogen and energy, and that it could have many biotechnological applications. They have tried producing large amounts of cyanophycin by putting the enzyme that makes it (known as cyanophycin synthetase) in everything from E. coli to tobacco, but without being able to make enough of it to be very useful.

Now, by combining two cutting-edge techniques, cryo-electron microscopy (at McGill’s Facility for Electron Microscopy Research) and X-ray crystallography, McGill researchers have, for the first time, been able to see the active enzyme in action.

“Until now scientists have been unable to understand the way bacterial cells store nitrogen in cyanophycin, simply because they couldn’t see the enzyme in action,” says Martin Schmeing, a Professor in McGill’s Department of Biochemistry and the senior author on a recent paper on the subject in Nature Chemical Biology. “By stitching 3D images of the at work into a movie, we were able to see how three different structural units (or domains), came together to create cyanophycin synthetase. It’s a surprising and very elegant example of a natural biomachine.”

The next steps in the research involve looking at the other enzymes used in the complete and degradation cycle of cyanophycin. Once the researchers are able to see them in action, this would potentially give them a complete structural understanding of the processes involved and would allow them to figure out how to turbocharge to make massive quantities of cyanophycin and related polymers for their green polymer biotech applications, such as in biodegradable water softeners and antiscalants or in the creation of heat-sensitive nanovesicles for use in targeted drug delivery.


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More information:
Itai Sharon et al, Structures and function of the amino acid polymerase cyanophycin synthetase, Nature Chemical Biology (2021). DOI: 10.1038/s41589-021-00854-y

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How bacteria create a piggy bank for the lean times (2021, October 14)
retrieved 15 October 2021
from https://phys.org/news/2021-10-bacteria-piggy-bank.html

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Spacewalking astronauts replace antenna after debris scare – Phys.Org

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This photo provided by NASA shows astronaut Tom Marshburn replaces a broken antenna outside the International Space Station after getting NASA’s all-clear for orbiting debris, on Thursday, Dec. 2, 2021. Marshburn and Kayla Barron completed the job Thursday. Credit: NASA via AP

Spacewalking astronauts replaced a broken antenna outside the International Space Station on Thursday after getting NASA’s all-clear for orbiting debris.

U.S. astronauts Tom Marshburn and Kayla Barron were supposed to complete the job Tuesday, but NASA delayed the spacewalk because of potentially threatening space junk. NASA later determined the astronauts were safe to go out, despite a slightly increased risk of a punctured suit from satellite wreckage.

But soon after the spacewalk ended, Mission Control notified the crew that the station would need to move into a slightly lower orbit Friday to avoid an old U.S. rocket fragment.

Last month, Russia destroyed an old satellite in a missile test, sending pieces everywhere. NASA isn’t saying whether that event was the source of the junk that delayed the spacewalk.

During the first National Space Council meeting under Vice President Kamala Harris this week, top U.S. government officials joined her in condemning Russia’s extensive debris-scattering last month. More than 1,700 sizable pieces of the shattered satellite are being tracked, with tens if not hundreds of thousands too small to see.

Barron reported at least 11 small debris strikes to the failed antenna that was removed during the spacewalk, with some of the holes looking old. The device—up there for more than 20 years—malfunctioned in September.

Marshburn, 61, became the oldest person to conduct a spacewalk. It was the fourth of his career. Barron, a 34-year-old space rookie, ventured out on her first. They flew up on SpaceX last month for a six-month stay. Two other Americans are aboard the space station, along with two Russians and one German.


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Space junk forces spacewalk delay, too risky for astronauts


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Spacewalking astronauts replace antenna after debris scare (2021, December 2)
retrieved 3 December 2021
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SpaceX launches 48 more Starlinks and two Earth-imaging satellites – CBS News

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A SpaceX Falcon 9 rocket boosted 48 more Starlink internet relay satellites into orbit Thursday, along with two BlackSky commercial Earth-imaging satellites. The flight marked the 27th Falcon 9 launch so far this year, a new record for the California-based rocket builder.

A SpaceX Falcon 9 rocket blasts off from the Cape Canaveral Space Force Station carrying 48 Starlink internet relay stations and two BlackSky Earth-imaging satellites.

William Harwood/CBS News


The Falcon 9’s first stage booster, making its ninth flight, thundered to life at 6:12 p.m. EST, smoothly pushing the 229-foot-tall rocket away from pad 40 at the Cape Canaveral Space Force Station atop 1.7 million pounds of thrust.

Eight minutes and 45 second later, the second stage and its 50-satellite cargo were safely in orbit. Just under an hour later, the two BlackSky satellites were released, followed by the 48 Starlinks about 25 minutes after that.

Meanwhile, the Falcon 9’s well-traveled booster successfully landed on an off-shore droneship to chalk up SpaceX’s 96th successful recovery, and its 73rd at sea.

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The nine first stage engines in the Falcon 9 booster put on a colorful show as the rocket climbed out of the lower atmosphere and the exhaust plume expanded in the lower pressure environment.

SpaceX


SpaceX has now launched 1,892 Starlinks as it populates a globe-spanning commercial constellation of internet relay satellites designed to provide broadband service to users anywhere in the world. Going into Thursday’s launch, 1,684 Starlinks were believed to be operational.

The two BlackSky imaging satellites joined eight others already in orbit, with two more scheduled for launch from New Zealand atop a Rocketlab booster later this month. BlackSky provides high-resolution imagery to commercial users as well as U.S. military and intelligence agencies.

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China regulator says more testing needed to certify C919 aircraft

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China‘s aviation regulator said on Friday that there is still a huge amount of testing to be done for the home-grown narrowbody C919 aircraft to be certified, raising doubt over planemaker COMAC’s year-end target.

So far, the C919, China’s attempt to rival Airbus SE and Boeing Co, has completed only 34 certification tests out of 276 planned, Yang Zhenmei, a Civil Aviation Administration of China (CAAC) official, told reporters.

Reuters in September reported COMAC has found it harder to meet certification and production targets for the C919 amid tough U.S. export rules, according to three people with knowledge of the programme.

China Eastern Airlines Corp Ltd said in August it expected to receive its first C919 by the end of the year, but that would require the model to be certified.

COMAC is years behind its initial certification schedule and it did not take the C919 to China’s biggest air show in Zhuhai in September.

C919 Chief Designer Wu Guanghui last month recommended CAAC continue to focus on certification as a priority for next year and asked it to step up resources to help with the delivery and commercial operations of the plane.

 

(Reporting by Stella Qiu in Beijing and Jamie Freed in Sydney; Editing by Kim Coghill)

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