“…These amino-acids are highly conserved residues among sHSP with lipochaperon activity 25 . The E60K, T79V, G82V and R99D substitutions of Lo18 correspond to the main conserved residues of the “ E LPG” motif, upstream of the β4 strand for the E60K substitution, the “L T IS G KRE” motif on the β5 strand for the T79V and G82V substitutions, and the “ R SERSYGSFR” motif on the β6/β7 strands for the R99Dsubstitution 25 . Figure 1 ( A ) Sequence alignment of Lo18 or modified proteins.…”
Section: Resultsmentioning
confidence: 99%
“…3 ). Because this tyrosine has been described as linking the two planes of the α-crystallin domain together 25 , the G82V substitution could disrupt the β -sandwich structure of the α-crystallin domain. In the R99D substitution, the aspartic acid in position 99 (99D-red) was no longer accessible to interact with the aspartic acid in position 90 (D90-blue) present on the β6 loop, compared to the original arginine (R99-red) (Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Few sHSPs have been described as performing both these activities, the mechanisms involved in lipochaperon activity are still very poorly understood. A recent study has shown that certain residues are highly conserved in sHSPs with lipochaperon activity 25 . In this context, the interaction between Lo18 sHsp and O. oeni membrane lipids was studied on the basis of the structure–function relationship (Table 2 ).…”
Section: Discussionmentioning
confidence: 99%
“…Previous studies have shown that after heat or ethanol stresses, Lo18 interacts as a dimer at the membrane level to rapidly stop increasing membrane fluidity 21 – 24 . Currently, few data are available in the literature on the molecular mechanisms involved in lipochaperon activity, either for Lo18 or for the other lipochaperon sHSPs 25 .…”
Section: Introductionmentioning
confidence: 99%
“…Recently, it has been observed that all sHSPs with lipochaperon activity have certain highly conserved amino-acids 25 . In order to assess the importance of these amino-acids, four of them (three located in the core of the protein and one located in an adjacent loop) were studied for their possible roles in maintaining the structure and functions of O. oeni sHSP Lo18.…”
To cope with environmental stresses, bacteria have developed different strategies, including the production of small heat shock proteins (sHSP). All sHSPs are described for their role as molecular chaperones. Some of them, like the Lo18 protein synthesized by Oenococcus oeni, also have the particularity of acting as a lipochaperon to maintain membrane fluidity in its optimal state following cellular stresses. Lipochaperon activity is poorly characterized and very little information is available on the domains or amino-acids key to this activity. The aim in this paper is to investigate the importance at the protein structure and function level of four highly conserved residues in sHSP exhibiting lipochaperon activity. Thus, by combining in silico, in vitro and in vivo approaches the importance of three amino-acids present in the core of the protein was shown to maintain both the structure of Lo18 and its functions.
“…These amino-acids are highly conserved residues among sHSP with lipochaperon activity 25 . The E60K, T79V, G82V and R99D substitutions of Lo18 correspond to the main conserved residues of the “ E LPG” motif, upstream of the β4 strand for the E60K substitution, the “L T IS G KRE” motif on the β5 strand for the T79V and G82V substitutions, and the “ R SERSYGSFR” motif on the β6/β7 strands for the R99Dsubstitution 25 . Figure 1 ( A ) Sequence alignment of Lo18 or modified proteins.…”
Section: Resultsmentioning
confidence: 99%
“…3 ). Because this tyrosine has been described as linking the two planes of the α-crystallin domain together 25 , the G82V substitution could disrupt the β -sandwich structure of the α-crystallin domain. In the R99D substitution, the aspartic acid in position 99 (99D-red) was no longer accessible to interact with the aspartic acid in position 90 (D90-blue) present on the β6 loop, compared to the original arginine (R99-red) (Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Few sHSPs have been described as performing both these activities, the mechanisms involved in lipochaperon activity are still very poorly understood. A recent study has shown that certain residues are highly conserved in sHSPs with lipochaperon activity 25 . In this context, the interaction between Lo18 sHsp and O. oeni membrane lipids was studied on the basis of the structure–function relationship (Table 2 ).…”
Section: Discussionmentioning
confidence: 99%
“…Previous studies have shown that after heat or ethanol stresses, Lo18 interacts as a dimer at the membrane level to rapidly stop increasing membrane fluidity 21 – 24 . Currently, few data are available in the literature on the molecular mechanisms involved in lipochaperon activity, either for Lo18 or for the other lipochaperon sHSPs 25 .…”
Section: Introductionmentioning
confidence: 99%
“…Recently, it has been observed that all sHSPs with lipochaperon activity have certain highly conserved amino-acids 25 . In order to assess the importance of these amino-acids, four of them (three located in the core of the protein and one located in an adjacent loop) were studied for their possible roles in maintaining the structure and functions of O. oeni sHSP Lo18.…”
To cope with environmental stresses, bacteria have developed different strategies, including the production of small heat shock proteins (sHSP). All sHSPs are described for their role as molecular chaperones. Some of them, like the Lo18 protein synthesized by Oenococcus oeni, also have the particularity of acting as a lipochaperon to maintain membrane fluidity in its optimal state following cellular stresses. Lipochaperon activity is poorly characterized and very little information is available on the domains or amino-acids key to this activity. The aim in this paper is to investigate the importance at the protein structure and function level of four highly conserved residues in sHSP exhibiting lipochaperon activity. Thus, by combining in silico, in vitro and in vivo approaches the importance of three amino-acids present in the core of the protein was shown to maintain both the structure of Lo18 and its functions.
To cope with environmental stresses, organisms, including lactic acid bacteria such as
O. oeni
, produce stress proteins called HSPs. In wine,
O. oeni
is constantly confronted by stress affecting its membrane fluidity. To survive through in these deleterious conditions,
O. oeni
synthesizes Lo18, a unique, small HSP which acts as a molecular chaperone and a lipochaperone. The molecular mechanism underlying its lipochaperone activity, particularly regarding membrane lipid composition, remains poorly understood. In this context, Lo18 lipochaperone activity and the associated modification in protein structure were studied during interaction with different liposomes from
O. oeni
cultures representing unstressed, stressed and stressed-adapted physiological states. The results showed that the presence of the membrane (whatever its nature) induces a modification of Lo18’s structure. Also, the presence of oleic acid and/or phosphatidylglycerol is important to favor Lo18-membrane interaction, allowing lipochaperone activity. This research enhances understanding of sHSP-membrane interactions in bacterial systems.
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