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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

Reactive oxygen species (ROS) level determination in sterile cyanobacterial growth medium. Fluorescence of the molecular probe, DCF, which is directly related to its oxidation state and to the amount of ROS in the medium, was used to measure total ROS levels (A.U., arbitrary units). Cyanobacterial media BG110, BG11 and BG110 + NH4+ were kept sterile under the same conditions of temperature and aeration as cyanobacterial cultures. Water was used as the control. White bars, water or medium without H2O2; grey bars, water or medium with 0.5 mM H2O2. Given the heterogeneity in DCF fluorescence between different experiments, the data shown are from a single experiment, but the observed pattern is typical (at least three separate observations). The bar values are means, and the error bars correspond to the standard deviation from three technical replicates.
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life-05-00130-f006: Reactive oxygen species (ROS) level determination in sterile cyanobacterial growth medium. Fluorescence of the molecular probe, DCF, which is directly related to its oxidation state and to the amount of ROS in the medium, was used to measure total ROS levels (A.U., arbitrary units). Cyanobacterial media BG110, BG11 and BG110 + NH4+ were kept sterile under the same conditions of temperature and aeration as cyanobacterial cultures. Water was used as the control. White bars, water or medium without H2O2; grey bars, water or medium with 0.5 mM H2O2. Given the heterogeneity in DCF fluorescence between different experiments, the data shown are from a single experiment, but the observed pattern is typical (at least three separate observations). The bar values are means, and the error bars correspond to the standard deviation from three technical replicates.

Mentions: These results combined indicate that Anabaena sp. PCC 7120 is dealing with oxidative stress even outside of the cells. This notion may not be surprising for cyanobacteria in defined ecological circumstances, such as in mats, biofilms, symbiotic associations or even when free-living in freshwater bodies or marine ecosystems, since competition with other microorganisms for nutrients and even other cyanobacteria for light may involve ROS release and attack. However, in controlled laboratory conditions, in which the organism is cultivated axenically, it becomes difficult to interpret the observation that Anabaena sp. PCC 7120 exports and accumulates such high amounts of functional ROS detoxifying agents. Consequently, we became interested in analysing the ROS usually formed in normal growth medium under ordinary cultivating conditions, but without the presence of cells. Thus, the three media used to grow Anabaena sp. PCC 7120 (BG110, BG11, BG110 + NH4+) were kept sterile in the same conditions as cyanobacterial cultures. ROS levels were determined using the fluorescent redox indicator, DCF (dichlorodihydrofluorescein) (Figure 6).


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)

Reactive oxygen species (ROS) level determination in sterile cyanobacterial growth medium. Fluorescence of the molecular probe, DCF, which is directly related to its oxidation state and to the amount of ROS in the medium, was used to measure total ROS levels (A.U., arbitrary units). Cyanobacterial media BG110, BG11 and BG110 + NH4+ were kept sterile under the same conditions of temperature and aeration as cyanobacterial cultures. Water was used as the control. White bars, water or medium without H2O2; grey bars, water or medium with 0.5 mM H2O2. Given the heterogeneity in DCF fluorescence between different experiments, the data shown are from a single experiment, but the observed pattern is typical (at least three separate observations). The bar values are means, and the error bars correspond to the standard deviation from three technical replicates.
© Copyright Policy
Related In: Results  -  Collection

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

life-05-00130-f006: Reactive oxygen species (ROS) level determination in sterile cyanobacterial growth medium. Fluorescence of the molecular probe, DCF, which is directly related to its oxidation state and to the amount of ROS in the medium, was used to measure total ROS levels (A.U., arbitrary units). Cyanobacterial media BG110, BG11 and BG110 + NH4+ were kept sterile under the same conditions of temperature and aeration as cyanobacterial cultures. Water was used as the control. White bars, water or medium without H2O2; grey bars, water or medium with 0.5 mM H2O2. Given the heterogeneity in DCF fluorescence between different experiments, the data shown are from a single experiment, but the observed pattern is typical (at least three separate observations). The bar values are means, and the error bars correspond to the standard deviation from three technical replicates.
Mentions: These results combined indicate that Anabaena sp. PCC 7120 is dealing with oxidative stress even outside of the cells. This notion may not be surprising for cyanobacteria in defined ecological circumstances, such as in mats, biofilms, symbiotic associations or even when free-living in freshwater bodies or marine ecosystems, since competition with other microorganisms for nutrients and even other cyanobacteria for light may involve ROS release and attack. However, in controlled laboratory conditions, in which the organism is cultivated axenically, it becomes difficult to interpret the observation that Anabaena sp. PCC 7120 exports and accumulates such high amounts of functional ROS detoxifying agents. Consequently, we became interested in analysing the ROS usually formed in normal growth medium under ordinary cultivating conditions, but without the presence of cells. Thus, the three media used to grow Anabaena sp. PCC 7120 (BG110, BG11, BG110 + NH4+) were kept sterile in the same conditions as cyanobacterial cultures. ROS levels were determined using the fluorescent redox indicator, DCF (dichlorodihydrofluorescein) (Figure 6).

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