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The Anabaena sp. PCC 7120 Exoproteome: Taking a Peek outside the Box.

Oliveira P, Martins NM, Santos M, Couto NA, Wright PC, Tamagnini P - Life (Basel) (2015)

Bottom Line: The evidence presented here shows that Anabaena sp.Furthermore, the activity of selected exoproteins associated with oxidative stress has been assessed, suggesting their involvement in redox homeostasis mechanisms in the extracellular space.Finally, we discuss our results in light of other cyanobacterial exoproteome studies and focus on the potential of exploring cyanobacteria as cell factories to produce and secrete selected proteins.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4150-180, Portugal. paulo.oliveira@ibmc.up.pt.

ABSTRACT
The interest in examining the subset of proteins present in the extracellular milieu, the exoproteome, has been growing due to novel insights highlighting their role on extracellular matrix organization and biofilm formation, but also on homeostasis and development. The cyanobacterial exoproteome is poorly studied, and the role of cyanobacterial exoproteins on cell wall biogenesis, morphology and even physiology is largely unknown. Here, we present a comprehensive examination of the Anabaena sp. PCC 7120 exoproteome under various growth conditions. Altogether, 139 proteins belonging to 16 different functional categories have been identified. A large fraction (48%) of the identified proteins is classified as "hypothetical", falls into the "other categories" set or presents no similarity to other proteins. The evidence presented here shows that Anabaena sp. PCC 7120 is capable of outer membrane vesicle formation and that these vesicles are likely to contribute to the exoproteome profile. Furthermore, the activity of selected exoproteins associated with oxidative stress has been assessed, suggesting their involvement in redox homeostasis mechanisms in the extracellular space. Finally, we discuss our results in light of other cyanobacterial exoproteome studies and focus on the potential of exploring cyanobacteria as cell factories to produce and secrete selected proteins.

No MeSH data available.


Related in: MedlinePlus

Catalase activity measured in cell-free extracts (total protein) or in concentrated exoproteomes of Anabaena sp. PCC 7120. Activities are expressed as units (defined as the amount of enzyme that catalyses the dissociation of 1 µmol of H2O2 per minute) per mg of total protein (left) or units per µg chlorophyll a (right).
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life-05-00130-f005: Catalase activity measured in cell-free extracts (total protein) or in concentrated exoproteomes of Anabaena sp. PCC 7120. Activities are expressed as units (defined as the amount of enzyme that catalyses the dissociation of 1 µmol of H2O2 per minute) per mg of total protein (left) or units per µg chlorophyll a (right).

Mentions: We have also extended our analyses to evaluate catalase activity (Figure 5). Our results indicate that some factor in the Anabaena sp. PCC 7120 growth medium does possess the capacity of decomposing H2O2 (Figure 5), likely catalase. These results validate the identification of Alr3090 in the exoproteome of Anabaena sp. PCC 7120 and further support the suggestion that a complex oxidative stress defence mechanism exists extracellularly in this cyanobacterium. Nevertheless, total catalase activity levels determined here are low as compared to what is described for other cyanobacteria [68,69], even when using total protein extracts (Figure 5). However, catalase has been shown not to be the main mechanism to cope with H2O2 by the filamentous, heterocyst-forming cyanobacterium, Anabaena sp. PCC 7120; instead, peroxiredoxins are reported to be the main H2O2 detoxifying pathway [70], one of which (Alr4641) has been identified in the exoproteome of Anabaena sp. PCC 7120 (see the discussion below).


The Anabaena sp. PCC 7120 Exoproteome: Taking a Peek outside the Box.

Oliveira P, Martins NM, Santos M, Couto NA, Wright PC, Tamagnini P - Life (Basel) (2015)

Catalase activity measured in cell-free extracts (total protein) or in concentrated exoproteomes of Anabaena sp. PCC 7120. Activities are expressed as units (defined as the amount of enzyme that catalyses the dissociation of 1 µmol of H2O2 per minute) per mg of total protein (left) or units per µg chlorophyll a (right).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390845&req=5

life-05-00130-f005: Catalase activity measured in cell-free extracts (total protein) or in concentrated exoproteomes of Anabaena sp. PCC 7120. Activities are expressed as units (defined as the amount of enzyme that catalyses the dissociation of 1 µmol of H2O2 per minute) per mg of total protein (left) or units per µg chlorophyll a (right).
Mentions: We have also extended our analyses to evaluate catalase activity (Figure 5). Our results indicate that some factor in the Anabaena sp. PCC 7120 growth medium does possess the capacity of decomposing H2O2 (Figure 5), likely catalase. These results validate the identification of Alr3090 in the exoproteome of Anabaena sp. PCC 7120 and further support the suggestion that a complex oxidative stress defence mechanism exists extracellularly in this cyanobacterium. Nevertheless, total catalase activity levels determined here are low as compared to what is described for other cyanobacteria [68,69], even when using total protein extracts (Figure 5). However, catalase has been shown not to be the main mechanism to cope with H2O2 by the filamentous, heterocyst-forming cyanobacterium, Anabaena sp. PCC 7120; instead, peroxiredoxins are reported to be the main H2O2 detoxifying pathway [70], one of which (Alr4641) has been identified in the exoproteome of Anabaena sp. PCC 7120 (see the discussion below).

Bottom Line: The evidence presented here shows that Anabaena sp.Furthermore, the activity of selected exoproteins associated with oxidative stress has been assessed, suggesting their involvement in redox homeostasis mechanisms in the extracellular space.Finally, we discuss our results in light of other cyanobacterial exoproteome studies and focus on the potential of exploring cyanobacteria as cell factories to produce and secrete selected proteins.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4150-180, Portugal. paulo.oliveira@ibmc.up.pt.

ABSTRACT
The interest in examining the subset of proteins present in the extracellular milieu, the exoproteome, has been growing due to novel insights highlighting their role on extracellular matrix organization and biofilm formation, but also on homeostasis and development. The cyanobacterial exoproteome is poorly studied, and the role of cyanobacterial exoproteins on cell wall biogenesis, morphology and even physiology is largely unknown. Here, we present a comprehensive examination of the Anabaena sp. PCC 7120 exoproteome under various growth conditions. Altogether, 139 proteins belonging to 16 different functional categories have been identified. A large fraction (48%) of the identified proteins is classified as "hypothetical", falls into the "other categories" set or presents no similarity to other proteins. The evidence presented here shows that Anabaena sp. PCC 7120 is capable of outer membrane vesicle formation and that these vesicles are likely to contribute to the exoproteome profile. Furthermore, the activity of selected exoproteins associated with oxidative stress has been assessed, suggesting their involvement in redox homeostasis mechanisms in the extracellular space. Finally, we discuss our results in light of other cyanobacterial exoproteome studies and focus on the potential of exploring cyanobacteria as cell factories to produce and secrete selected proteins.

No MeSH data available.


Related in: MedlinePlus